WO2004057698A9 - Antennas with reduced space and improved performance - Google Patents

Antennas with reduced space and improved performance

Info

Publication number
WO2004057698A9
WO2004057698A9 PCT/US2003/040663 US0340663W WO2004057698A9 WO 2004057698 A9 WO2004057698 A9 WO 2004057698A9 US 0340663 W US0340663 W US 0340663W WO 2004057698 A9 WO2004057698 A9 WO 2004057698A9
Authority
WO
WIPO (PCT)
Prior art keywords
antenna
ofthe
substrate
conductor
antenna element
Prior art date
Application number
PCT/US2003/040663
Other languages
French (fr)
Other versions
WO2004057698A3 (en
WO2004057698A2 (en
Inventor
Vaneet Pathak
Gregory Poilasne
Laurent Desclos
Sebastian Rowson
Jeff Shamblin
Original Assignee
Ethertronics Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US10/322,196 external-priority patent/US7084813B2/en
Priority claimed from US10/375,423 external-priority patent/US8059047B2/en
Priority claimed from US10/643,102 external-priority patent/US7616164B2/en
Application filed by Ethertronics Inc filed Critical Ethertronics Inc
Priority to AU2003303179A priority Critical patent/AU2003303179A1/en
Priority to EP03808509A priority patent/EP1579529A4/en
Publication of WO2004057698A2 publication Critical patent/WO2004057698A2/en
Publication of WO2004057698A9 publication Critical patent/WO2004057698A9/en
Publication of WO2004057698A3 publication Critical patent/WO2004057698A3/en

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00Antenna arrays or systems
    • H01Q21/28Combinations of substantially independent non-interacting antenna units or systems
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00Details of, or arrangements associated with, antennas
    • H01Q1/12Supports; Mounting means
    • H01Q1/22Supports; Mounting means by structural association with other equipment or articles
    • H01Q1/24Supports; Mounting means by structural association with other equipment or articles with receiving set
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00Details of, or arrangements associated with, antennas
    • H01Q1/36Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00Details of, or arrangements associated with, antennas
    • H01Q1/52Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00Details of, or arrangements associated with, antennas
    • H01Q1/52Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure
    • H01Q1/521Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure reducing the coupling between adjacent antennas
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/10Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00Antenna arrays or systems
    • H01Q21/24Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/30Arrangements for providing operation on different wavebands
    • H01Q5/307Individual or coupled radiating elements, each element being fed in an unspecified way
    • H01Q5/342Individual or coupled radiating elements, each element being fed in an unspecified way for different propagation modes
    • H01Q5/357Individual or coupled radiating elements, each element being fed in an unspecified way for different propagation modes using a single feed point
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04Resonant antennas
    • H01Q9/0407Substantially flat resonant element parallel to ground plane, e.g. patch antenna
    • H01Q9/0442Substantially flat resonant element parallel to ground plane, e.g. patch antenna with particular tuning means
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04Resonant antennas
    • H01Q9/16Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole
    • H01Q9/26Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole with folded element or elements, the folded parts being spaced apart a small fraction of operating wavelength
    • H01Q9/265Open ring dipoles; Circular dipoles
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04Resonant antennas
    • H01Q9/30Resonant antennas with feed to end of elongated active element, e.g. unipole
    • H01Q9/42Resonant antennas with feed to end of elongated active element, e.g. unipole with folded element, the folded parts being spaced apart a small fraction of the operating wavelength

Definitions

  • the present invention relates generally to the field of wireless communications, and particularly to the size reduction and performance improvement of capacitively loaded magnetic dipole antennas.
  • An antenna is an electrical conductor or array of conductors that radiates (transmits and/or receives) electromagnetic waves.
  • a magnetic dipole antenna is a loop antenna that radiates electromagnetic waves in response to current circulating through the loop. Electromagnetic waves are often referred to as radio waves. Most antennas are resonant devices, which operate efficiently over a relatively narrow frequency band. An antenna must be tuned to the same frequency band that the system using it operates in, otherwise reception and/or transmission will be impaired.
  • the bandwidth of an antenna refers to the range of frequencies over which the antenna can operate satisfactorily. It is usually defined by impedance mismatch but it can also be defined by pattern features such as gain, beamwidth, etc.. Antenna designers quickly assess the feasibility of an antenna requirement by expressing the required bandwidth as a percentage ofthe center frequency ofthe band. Different types of antennas have different bandwidth limitations. Normally, a fairly large volume is required if a large bandwidth is desired. Accordingly, the present invention addresses the needs of small compact antenna with wide bandwidth.
  • the present invention provides a versatile antenna design that resonates at more than one frequency, that is it is multiresonant, and that may be adapted to a variety of packaging configurations.
  • the antenna contains one or more elements.
  • Elements are the conductive parts of an antenna system that determine the antenna's electromagnetic characteristics.
  • the element of an magnetic dipole antenna is designed so that it resonates at a predetermined frequency as required by the application for which it is being used.
  • the antenna's resonant frequency is dependant on the capactive and inductive properties ofthe antenna elements.
  • the capacitive and inductive properties ofthe antenna elements are dictated by the dimensions ofthe antenna elements and their interrelations.
  • the radiated electromagnetic wave from an antemia is characterized by the complex vector E x H in which E is the electric field and H is the magnetic field.
  • Polarization describes the orientation ofthe radiated wave's electric field. For maximum performance, polarization must be matched to the orientation ofthe radiated field to receive the maximum field intensity ofthe electromagnetic wave. If it is not oriented properly, a portion ofthe signal is lost, known as polarization loss.
  • linear polarization the electric field vector lies on a straight line that is either vertical (vertical polarization), horizontal (horizontal polarization) or on a 45 degree angle (slant polarization). If the radiating elements are dipoles, the polarization simply refers to how the elements are oriented or positioned. If the radiating elements are vertical, then the antenna has vertical polarization and if horizontal, it has horizontal polarization. In circular polarization two orthogonal linearly polarized waves of equal amplitude and 90 degrees out of phase are radiated simultaneously.
  • Magnetic dipole antennas can be designed with more than one antenna element. It is often desirable for an antenna to resonate at more than one frequency. For each desired frequency, an antenna element will be required. Different successive resonances occur at the frequencies fi, f 2 , £... f n . These peaks correspond to the different electromagnetic modes excited inside the structure.
  • the antenna can be designed so that the frequencies provide the antenna with a wide bandwidth of coverage by utilizing overlapping or nearly overlapping frequencies. However, antennas that have an wider bandwidth than a monoresonant antenna often have a correspondingly increased size.
  • Small antennas are desired for use in and with portable wireless communication devices.
  • classical antenna structures a certain physical volume is required to produce a resonant antenna structure at a particular radio frequency and with a particular bandwidth.
  • bandwidth and frequency requirements dictated the volume of an antenna, and therefore to some extent placed limitations upon the design of wireless devices.
  • Many present day applications require that antennas provide large bandwidth, efficiency, and isolation in as small form factor as possible.
  • the present invention includes antenna elements and antenna element arrangements having a generally low profile, improved isolation, and a large bandwidth in comparison to prior art antennas.
  • the antenna elements include both capacitive and inductive parts. Each element provides a frequency or band of frequencies to the antenna.
  • the preferred embodiments relate to a capacitively loaded magnetic dipole
  • CLMD CLMD antenna having antenna elements having improved grounding characteristics to improve isolation.
  • Other embodiments provide a reduction in the footprint ofthe antenna elements while maintaining the performance characteristics by providing a greater surface area on either a top, middle or bottom portion of a CLMD antenna.
  • Further embodiments provide antenna element arrangements with improved radiation efficiency by providing metallic reflectors on the sides of antenna elements.
  • the isolation characteristics of antenna elements are improved through the use of coplanar wave guides.
  • the bandwidth may be improved through the use of stubs resonators.
  • the bandwidth ofthe antenna elements is improved without reducing isolation or shielding by providing a variable gap between two portions of the antenna elements.
  • shielding ofthe antenna element is improved by providing a shield between at least a portion ofthe antenna element and a ground plane.
  • a lower profile is achieved by positioning the antenna elements in a coplanar manner with a ground plane.
  • the isolation ofthe antenna element is improved by positioning the antenna element in a cutout provided in the ground plane.
  • the antenna element arrangement may achieve a larger bandwidth by positioning two or more antenna elements in a plurality of cutouts in the ground plane. Further, a savings in volume may be achieved by positioning other components within the footprint ofthe antenna element.
  • the present invention includes a wireless device comprising: a first portion; a second portion, the first and second portion disposed to effectuate a capacitive area; and a third portion, the third portion coupled to the first portion and to the second portion to effectuate an inductive area, wherein the third portion comprises a length having a first end and a second end, wherein the length is longer than a straight line distance between the first end and the second end, and wherein the first portion, the second portion, and the third portion define a capacitively coupled dipole antenna.
  • the present invention includes a dipole antenna comprising: a first portion; a second portion, the first and second portion disposed to create a capacitive area; and a third portion, the third portion comprising one or more portion, the third portion coupled to the first portion and to the second portion to create an inductive area, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end.
  • One or more portion ofthe third portion may be disposed relative to the first portion and the second portion in a non- parallel relationship.
  • One or more portion ofthe third portion may be disposed relative to the first portion and the second portion in a parallel relationship.
  • the first and second portion may be disposed in a generally coplanar relationship, and one or more portion ofthe third portion may be disposed in a plane that is in an angular relationship relative to the coplanar relationship ofthe first and second portion.
  • the first portion, the second portion, and the third portion may be disposed on or above a ground plane.
  • the antenna may include a substrate, wherein the first portion and the second portion are coupled to the substrate.
  • the antenna may include a FR4 substrate.
  • the FR4 substrate may be defined by a periphery, wherein within the periphery the FR4 substrate defines a void, and wherein the capacitive area generally spans the void.
  • the first portion, the second portion, and the third portion may be coupled to crate a capacitively coupled dipole antenna.
  • the present invention includes a system, comprising: a dipole antenna including, a first portion; a second portion, the first and second portion disposed in a relationship to create a capacitive area; and a third portion, the third portion coupled to the first portion and to the second portion and disposed to create an inductive area, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end.
  • the antenna may further include a high dissipation factor substrate.
  • the antenna may include an FR4 substrate.
  • the first and second portion may be coupled to the FR4 substrate, wherein the FR4 substrate is defined by a periphery, wherein within the periphery the FR4 substrate defines a void, and wherein the capacitive area generally spans the void.
  • the system may comprise a wireless communications device.
  • the present invention includes a capacitively couple dipole antenna, comprising: capacitance means for creating a capacitance; and inductive means for creating an inductance.
  • the antenna may comprise a first portion, a second portion, and a third portion, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end.
  • the antenna may comprise a substrate.
  • the first and second portion may be coupled to the substrate, wherein the substrate is defined by a periphery, wherein within the periphery the substrate defines a void, wherein the capacitance generally spans the void.
  • the present invention includes a method for creating a resonance in a resonant circuit comprising the steps of: providing a first portion; providing a second portion; disposing the first and second portion to crate a capacitive area; and providing a third portion, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end; and coupling the third portion to the first portion and to the second portion to create an inductive area.
  • the method may further include the step of: providing a high dissipation factor substrate, wherein the high dissipation factor substrate is defined by a periphery, wherein within the periphery the high dissipation factor substrate defines a void, and wherein the capacitive area generally spans the void.
  • the basic antenna element comprises a substantially planar structure with a planar conductor and a pair of parallel elongated conductors, each having a first end electrically connected to the planar conductor. Additional elements may be coupled to the basic element in an array. In this way, individual antenna structures share common elements and volumes, thereby increasing the ratio of relative bandwidth to volume.
  • Figure 1 conceptually illustrates the antenna designs ofthe present invention.
  • Figure 2 illustrates the increased overall bandwidth achieved with a multiresonant antenna design.
  • Figure 3 is an equivalent circuit for a radiating structure.
  • Figure 4 is an equivalent circuit for a multiresonant antenna structure.
  • Figure 5 A illustrates a three-dimensional view of an embodiment of an antenna element
  • Figure 5B illustrates a side-view ofthe antenna element illustrated in Figure 5 A;
  • Figure 6A illustrates a side-view of an embodiment of antenna element in accordance with the present invention
  • Figure 6B illustrates a side-view of another embodiment of antenna element in accordance with the present invention.
  • Figure 6C illustrates a side-view of yet another embodiment of antenna element in accordance with the present invention.
  • Figure 7A illustrates a side-view of another embodiment of an antenna element in accordance with the present invention.
  • Figure 7B illustrates a side-view of various embodiments ofthe bottom portion of the antenna element illustrated in Figure 3 A;
  • Figure 7C illustrates a side-view of another embodiment of an antenna element in accordance with the present invention.
  • Figure 7D illustrates a side-view of various embodiments ofthe bottom portion of the antenna element illustrated in Figure 3C;
  • Figure 7E illustrates a side-view of another embodiment of an antenna element in accordance with the present invention.
  • Figure 7F illustrates a side-view of various embodiments ofthe bottom portion of the antenna element illustrated in Figure 3E;
  • Figure 8 A illustrates a three-dimensional view of an embodiment of an antenna element arrangement in accordance with the present invention
  • Figure 8B illustrates a side-view ofthe antenna element arrangement illustrated in Figure 4A;
  • Figure 8C illustrates a top- view ofthe antenna element arrangement illustrated in Figures 4 A and 4B;
  • Figure 9A illustrates a top-view of an embodiment of an antenna element arrangement in accordance with the present invention.
  • Figure 9B illustrates a radio frequency (RF) schematic ofthe antenna element arrangement of Figure 5 A;
  • Figure 9C illustrates a top- view of another embodiment of an antenna element arrangement in accordance with the present invention.
  • Figure 9D illustrates a radio frequency (RF) schematic ofthe antenna element arrangement of Figure 5C;
  • Figure 9E illustrates a top-view of another embodiment of an antenna element arrangement in accordance with the present invention.
  • Figure 9F illustrates an embodiment of a radio frequency (RF) schematic ofthe antenna element arrangement of Figure 5E;
  • Figure 9G illustrates another embodiment of a radio frequency (RF) schematic of the antenna element arrangement of Figure 5E;
  • Figure 9H illustrates yet another embodiment of a radio frequency (RF) schematic ofthe antenna element arrangement of Figure 5E;
  • RF radio frequency
  • Figure 10A illustrates a side-view of an embodiment of an antenna element
  • Figures 10B and 6C illustrate cross-sectional views taken along VIB-NIB ofthe antenna element illustrated in Figure 10 A;
  • Figure 10D illustrates a side-view of an embodiment of an antenna element in accordance with the present invention
  • Figure 11 A illustrates a side-view of another embodiment of an antenna element in accordance with the present invention.
  • Figure 1 IB illustrates a side-view of still another embodiment of an antenna element in accordance with the present invention
  • Figure 11C illustrates a side-view of yet another embodiment of an antenna element in accordance with the present invention.
  • Figure 12A illustrates a side-view of an embodiment of an antenna element in accordance with the present invention
  • Figure 12B illustrates a side-view of another embodiment of an antenna element in accordance with the present invention.
  • Figure 12C illustrates a side-view of yet another embodiment of an antenna element in accordance with the present invention.
  • Figure 12D illustrates a side-view of still another embodiment of an antenna element in accordance with the present invention.
  • Figure 13 A illustrates a side-view of an embodiment of an antenna element arrangement in accordance with the present invention
  • Figure 13B illustrates a side-view of another embodiment of an antenna element arrangement in accordance with the present invention.
  • Figure 13C illustrates a side-view of still another embodiment of an antenna element arrangement in accordance with the present invention.
  • Figure 13D illustrates a side-view of yet another embodiment of an antenna element arrangement in accordance with the present invention.
  • Figure 14 illustrates a three-dimensional view of an embodiment of an antenna element arrangement in accordance with the present invention
  • Figure 15 A illustrates a top view of an embodiment of an antenna element arrangement in accordance with the present invention
  • Figure 15B illustrates a top view of another embodiment of an antenna element arrangement in accordance with the present invention
  • Figure 16A illustrates a top view of an embodiment of an antenna element arrangement in accordance with the present invention
  • Figure 16B illustrates a top view of another embodiment of an antenna element arrangement in accordance with the present invention.
  • Figure 17 illustrates a top view of still another embodiment of an antenna element arrangement in accordance with the present invention.
  • Figures 18 A-B illustrate a respective three-dimensional and side view of a capacitively loaded dipole antenna.
  • Figure 18C illustrates a three dimensional view of a low profile/small form factor capacitively loaded dipole antenna.
  • Figure 19 illustrates a three dimensional view of a low profile/small form factor capacitively loaded dipole antenna.
  • Figures 20A-B illustrate three dimensional views of a low profile/small form factor capacitively loaded dipole antenna.
  • Figure 21 illustrates a low profile/small form factor antenna in accordance with the principles ofthe present invention.
  • Figure 22 illustrates two low profile/small form factor antennas in accordance with the principles ofthe present invention coupled together.
  • Figure 23 illustrates a basic radiating structure utilized in an embodiment ofthe present invention.
  • Figure 24 illustrates a dual-mode antenna in accordance with an embodiment ofthe present invention.
  • Figure 25 illustrates a multimode antenna in accordance with another embodiment ofthe present invention.
  • Figure 26 illustrates an antenna in accordance with the present invention that is formed flat on a substrate.
  • Figure 27 illustrates an antenna in accordance with an embodiment ofthe present invention with returns for ground and a feed.
  • Figures 28A-C illustrate the use of vias to provide feeds and shorts for an antenna in accordance with an embodiment ofthe present invention.
  • Figures 29A-C illustrate a dual frequency antenna in accordance with an embodiment ofthe present invention with side-by-side elements.
  • Figure 30 illustrates a dual frequency antenna in accordance with an embodiment of the present invention with nested elements.
  • Figure 31 illustrates an antenna in accordance with an embodiment ofthe present invention similar to that of Fig. 30 with an additional capacitive element to provide an additional resonant frequency.
  • Figures 32A-B illustrate a two-sided antenna in accordance with an embodiment of the present invention with three frequencies on one face of a substrate and a single frequency on the other face.
  • Figures 33 A-B illustrate an antenna in accordance with an embodiment ofthe present invention with conductors formed on the edge as well as the face of a substrate.
  • Figures 34 A-B illustrate a multifrequency planar antenna in accordance with an embodiment ofthe present invention on a primary substrate with an additional radiating element on a perpendicular secondary substrate.
  • Figures 35A-B illustrate antennas in accordance with an embodiment ofthe present invention with multiple secondary substrates.
  • Figure 36 illustrates an antenna in accordance with an embodiment ofthe present invention with an extended radiating element.
  • Figure 37 illustrates an antenna in accordance with an embodiment ofthe present invention with a pair of extended radiating elements.
  • Figure 38 shows the antenna of Fig. 37 within an enclosure in accordance with an embodiment ofthe present invention.
  • Figure 39 illustrates an antenna similar to that of Fig. 37 with additional radiating elements on perpendicular secondary substrates in accordance with an embodiment ofthe present invention.
  • Figure 40 shows the antenna of Fig. 39 within an enclosure in accordance with an embodiment ofthe present invention.
  • Figure 41 illustrates an antenna structure in accordance with an embodiment ofthe present invention with two radiating elements at opposite ends of a substrate.
  • Figure 42 illustrates a laptop computer in accordance with an embodiment ofthe present invention with multiple radiating elements.
  • Figure 43 illustrates an antenna in accordance with an embodiment ofthe present invention printed on a substrate with a milled groove between the conductors.
  • Figure 44 illustrates a multifrequency antenna in accordance with an embodiment of the present invention with a plurality of milled grooves.
  • Figure 45 illustrates an alternative method of fabricating an antenna structure in accordance with an embodiment ofthe present invention.
  • the disclosed embodiments ofthe present invention include antenna elements and antenna element arrangements having a generally low profile, improved isolation, and providing a larger bandwidth.
  • the volume to bandwidth ratio is one ofthe most important constraints in modern antenna design.
  • the physical volume of an antenna can place severe constraints on the design of small electronic devices.
  • One approach to increasing this ratio is to re-use the volume for different modes. Some designs already use this approach, even though the designs do not optimize the volume to bandwidth ratio.
  • two modes are generated using the same physical structure, although the modes do not use exactly the same volume. The current repartition ofthe two modes is different, but both modes nevertheless use a common portion ofthe total available volume ofthe antenna.
  • This concept of utilizing the physical volume ofthe antenna for a plurality of antenna modes is illustrated generally by the Venn Diagram of Figure 1.
  • the physical volume ofthe antenna (“N") has two radiating modes.
  • the physical volume associated with the first mode is designated W
  • that associated with the second mode is designated V '. It can be seen that a portion ofthe physical volume, designated 'N ⁇ j2 ', is common to both ofthe modes.
  • K law The concept of volume reuse and its frequency dependence are expressed with reference to "K law".
  • K law The general K law is defined by the following:
  • Af / f K » V/ ⁇ 3 [0098] wherein ⁇ f/f is the normalized frequency bandwidth, ⁇ is the wavelength, and the term A represents the physical volume that will enclose the antenna. This volume so far has not been optimized and no discussion has been made on the real definition of this volume and the relation fr the K factor.
  • Km o d a i is defined by the mode volume N; and the corresponding mode bandwidth:
  • K moda i is thus a constant related to the volume occupied by one electromagnetic mode.
  • K effect i ve is defined by the union ofthe mode volumes Ni U N 2 U..N; and the cumulative bandwidtr
  • ⁇ t ⁇ f / / f / /r ⁇ e ⁇ . (v v 2 .v / )/ ⁇ where ⁇ is the wavelength ofthe central frequency.
  • K effect i ve is a constant related to the minimum volume occupied by the different excited modes taking into account the fact that the modes share a part ofthe volume.
  • the different frequencies f; must be very close in order to have nearly overlapping bandwidths.
  • Kphysicai or Kobserved is defined by the physical volume 'V ofthe antenna and the overall antenna bandwidth:
  • Kphysic a i or K observed is the most important K factor since it takes into account the real physical parameters and the usable bandwidth.
  • K p h ys icai is also referred to as Kobserved since it is the only K factor that can be calculated experimentally. In order to have the modes confined within the physical volume ofthe antenna, Kphysicai must be lower than Keffective- However these K factors are often nearly equal.
  • Kphy s ic a i is approximately equal to K effect i ve and s also approximately equal to the smallest Kmodai- It should be noted that confining the modes inside the antenna is important in order to have a well-isolated antenna.
  • Figure 2 shows the observed return loss of a multiresonant structure. Different successive resonances occur at the frequencies f ls f 2 , fj... f n . These peaks correspond to the different electromagnetic modes excited inside the structure. Figure 2 illustrates the relationship between the physical, or observed, K and the bandwidth over ft to f n .
  • FIG. 3 For a particular radiating mode with a resonant frequency at fi, we can consider the equivalent simplified circuit LiCi shown in Figure 3. By neglecting the resistance in the equivalent circuit, the bandwidth ofthe antenna is simply a function ofthe radiation resistance. The circuit of Figure 3 can be repeated to produce an equivalent circuit for a plurality of resonant frequencies.
  • Figure 4 illustrates a multimode antenna represented by a plurality of inductance(L)/capacitance(C) circuits. At the frequency ft only the circuit LiCi is resonating. Physically, one part ofthe antenna structure resonates at each frequency within the covered spectrum. By utilizing antenna elements with overlapping resonance frequencies of ft to f n , an antenna in accordance with the present invention can cover frequencies 1 to n. Again, neglecting real resistance ofthe structure, the bandwidth of each mode is a function ofthe radiation resistance.
  • the antenna volume is reused for the different resonant modes.
  • One embodiment ofthe present invention utilizes a capacitively loaded microstrip type of antenna as the basic radiating structure. Modifications of this basic structure will be subsequently described.
  • the elements ofthe multimode antenna structures have closely spaced resonance frequencies.
  • FIGs 5A and 5B illustrate an embodiment of a capacitively loaded magnetic dipole (CLMD) antenna in accordance with the principles ofthe present invention.
  • the antenna element 10 includes a top portion 12, a middle portion 14 and a bottom portion 16. Each portion 12, 14, 16 may be a two-dimensional plate or a one-dimensional element.
  • the top portion 12 and the middle portion 14 form a capacitive component 18 ofthe antenna element 10.
  • a loop between the middle portion 14 and the bottom portion 16 forms an inductive component 20 ofthe antenna element 10.
  • the antenna element 10 is connected to a grounding plane 22 by a grounding point 24.
  • a feeding line 26 provides power to the antenna element 10.
  • Figure 6A illustrates a side-view of an antenna element 28 similar to the antenna element 10 described above with reference to Figures 5 A and 5B.
  • the antenna element 28 includes a top portion 30, middle portion 32 and bottom portion 34 forming a capacitive component and an inductive component.
  • the embodiment illustrated in Figure 6A provides improved grounding ofthe antenna element 10 to a grounding plane (not shown in Figure 6 A) through an elongated grounding point 36.
  • the elongated grounding point 36 illustrated in Figure 6 A extends from one end ofthe bottom portion 34 inward by a predetermined length.
  • the size ofthe grounding point 36 may be selected for the desired grounding characteristics ofthe antenna element 28.
  • the embodiment illustrated in Figure 6 A provides a larger surface area for the grounding ofthe antenna element 28.
  • FIG. 6B illustrates another embodiment of an antenna element with improved grounding characteristics.
  • an antenna element 38 has a top portion 40, a middle portion 42 and a bottom portion 44.
  • the antenna element 38 is provided with a plurality of grounding points 46 extending downward from the bottom portion 44 for improved grounding ofthe antenna element 38.
  • four grounding points 46 are provided.
  • the four grounding points 46 are positioned in an equally spaced apart configuration on one side ofthe bottom portion 44.
  • FIG. 6C illustrates yet another embodiment of an antenna element with improved grounding characteristics.
  • an antenna element 48 has a top portion 50, a middle portion 52 and a bottom portion 54.
  • the antenna element 48 is provided with a pair of grounding points 56 extending downward from the bottom portion 44.
  • the two grounding points 46 are positioned at one end and the middle ofthe bottom portion 44 for improved grounding ofthe antenna element 48.
  • FIG. 7A illustrates a side-view of a CLMD antenna element adapted to provide improved performance while maintaining a relatively small package size or footprint.
  • the illustrated antenna element 58 includes a top portion 60, a middle portion 62 and a bottom portion 64. While the top portion 60 and the middle portion 62 are similar to those illustrated in the above-described embodiments, the embodiment illustrated in Figure 7A includes a bottom portion 64 having a N-shaped ridge pattern. The ridged pattern ofthe bottom portion 64 effectively provides a greater surface area for the bottom portion 64 without increasing the footprint ofthe antenna element 58.
  • the bottom of one or more ridge may serve as a grounding point, other embodiments, as illustrated in Figure 7A, a separate grounding point may be provided.
  • improved performance is achieved without increasing the size ofthe antenna element.
  • Figure 7B illustrates a variety of ridged patterns which may be applied to the bottom portion 64 ofthe antenna element 58 illustrated in Figure 7 A. As illustrated in Figure 7B, the size and shape ofthe ridges maybe varied to achieve desired performance characteristics of the antenna element.
  • FIG. 7C illustrates another embodiment of an CLMD antenna element with improved performance without increasing or modifying the footprint.
  • the antenna element 66 illustrated in Figure 7C includes a top portion 68 and a middle portion 70 similar to those described above.
  • the antenna element 66 includes a bottom portion 72 having block ridges formed thereon.
  • the block ridges may be formed of a variety of shapes and sizes to provide the desired performance characteristics for the antenna element 66.
  • FIG. 7E illustrates yet another embodiment of an CLMD antenna element with improved performance without improved footprint.
  • the antenna element 74 illustrated in Figure 3E includes a top portion 76 and a middle portion 78 similar to those described above.
  • the antenna element 74 includes a bottom portion 80 having saw-tooth ridges formed thereon. As illustrated in Figure 3F, the saw-tooth ridges may be formed of a variety of shapes and sizes to provide the desired performance characteristics for the antenna element 66.
  • Figure 8A-8C illustrate an antenna element arrangement for providing a different field distribution and increased grounding ofthe antenna element.
  • the antenna element arrangement 82 includes an antenna element 84 grounded on a grounding plane 86 by a pair of grounding points 88, 90.
  • the antenna element 84 is positioned substantially perpendicular to the plane ofthe grounding plane 86.
  • a metallic reflector 92, 94 is provided on each side of the antenna element 84.
  • the reflectors 92, 94 are positioned substantially perpendicular to the plane ofthe grounding plane 86 and substantially perpendicular to the plane ofthe antenna element 84.
  • the metallic reflectors 92, 94 serve to improve the radiation efficiency ofthe antenna element 84 by altering the field distribution.
  • FIG. 9A illustrates an embodiment of an antenna element arrangement in accordance with the present invention.
  • the antenna element arrangement 96 includes an antenna element 98 positioned atop a ground plane 100 and grounded through a ground pad 102.
  • a coplanar wave guide (CPWG) 104 is provided on the board ofthe communication system to feed the antenna element 98.
  • CPWG's are well known to those skilled in the art.
  • the CPWG 104 provides the antenna element 98 with improved isolation characteristics.
  • Figure 9B illustrates a radio frequency (RF) schematic corresponding to the embodiment illustrated in Figure 9 A. As noted above, the CPWG 104 is in communication with the antenna element 98.
  • RF radio frequency
  • FIG. 9C illustrates another embodiment of an antenna element arrangement in accordance with the present invention.
  • the arrangement 106 includes an antenna element 108 positioned atop a ground plane 110 and grounded through a ground pad 112.
  • a CPWG 114 is provided in communication with the antenna element 108.
  • the arrangement 106 includes a single-stub resonator 116. The position, line, and width ofthe stub 116 on the line (CPWG) are dependent upon the input impedance ofthe antenna. Stubs are well known to those skilled in the art and can be either open-circuited or short-circuited.
  • the arrangement 106 may include any number of stubs 116. The number of studs may be selected depending on the bandwidth requirements ofthe antenna element 108.
  • FIG. 9D illustrates an RF schematic ofthe embodiment illustrated in Figure 9C.
  • FIG. 9E illustrates yet another embodiment of an antenna element arrangement in accordance with the present invention.
  • the arrangement 118 includes an antenna element 120 positioned atop a ground plane 122 and grounded through a ground pad 124.
  • a CPWG 126 is provided in communication with the antenna element 120.
  • the arrangement 118 includes two stubs 128a, 128b.
  • the two stubs 128a, 128b create two different resonant frequencies, which may be used to improve the bandwidth ofthe antenna element 120.
  • the position, line, and width ofthe stub on the line (CPW) are dependent upon the input impedance ofthe antenna.
  • Figures 9F-9H illustrate various embodiments of radio frequency (RF) schematics ofthe antenna element arrangement described above with reference to Figure 9E.
  • RF radio frequency
  • FIG 10A illustrates an antenna element similar to that described above with reference to Figures 5A and 5B.
  • the antenna element 130 includes a top portion 132 and a middle portion 134 that are separated by a gap of size d.
  • An electric field 136 is formed in the gap between the top portion 132 and the middle portion 134 when the antenna element is charged.
  • the size ofthe gap, d affects the confinement ofthe electric field 136 and, thus, the isolation and bandwidth ofthe antenna element 130.
  • a smaller gap size, d results in a more confined electric field, providing increased isolation and shielding for the antenna element 130.
  • a larger gap size, d results in a less confined electric field 136, providing reduced isolation and shielding, but a larger bandwidth.
  • Figures 10B and IOC are cross-sectional views along NLB-VIB of Figure 10A and illustrate the shape ofthe electric field 136 with variations is the size ofthe gap.
  • Figure 10B illustrates an electric field for a relatively small gap size
  • Figure IOC illustrates the electric field for a relatively large gap size.
  • FIG. 10D illustrates an embodiment of an antenna element adapted to provide greater bandwidth without reducing shielding.
  • the illustrated antenna element 138 includes a top portion 140, a middle portion 142 and a bottom portion 144.
  • the middle portion 142 is angled downward as it protrudes inward. This angled configuration results in a tapered gap 146 between the top portion 140 and the middle portion 142.
  • the tapered gap 146 provides the antenna element 138 with greater bandwidth capability without sacrificing shielding.
  • Figures 11 A-l IC illustrate additional embodiments of antenna elements having variable gaps between the top portions and the middle portions.
  • Figure 11 A illustrates an antenna element 148 having a top portion 150 and a middle portion 152.
  • the middle portion 152 is provided with a downwardly stepped configuration to provide a gap 154 with a variable size between the top portion 150 and the middle portion 152.
  • the embodiment illustrated in Figure 11 A is provided with a middle portion 152 having three steps, other embodiments may have any practical number of steps.
  • Figure 1 IB illustrates an antenna element 156 having a top portion 158 and a middle portion 160.
  • the middle portion 160 is upwardly angled to provide a tapered gap 162 with a variable size between the top portion 158 and the middle portion 160.
  • Figure 1 IC illustrates an antenna element 166 having a top portion 168 and a middle portion 170.
  • the middle portion 170 is provided with a upwardly stepped configuration to provide a gap 172 with a variable size between the top portion 168 and the middle portion 170.
  • FIGS 12A-12D illustrate further embodiments of antenna elements in accordance with the present invention.
  • the illustrated embodiments provide antenna elements with reduced sizes (or footprints) without a decrease in performance.
  • Figure 12A illustrates an antenna element 174 with a top portion 176, a middle portion 178 and a bottom portion 180.
  • a larger surface area for the middle portion 178 is achieved through a ridged configuration.
  • the middle portion 178 is provided with a plurality of block ridges to maintain the electric field strength between the top portion 176 and the middle portion 178 while reducing the footprint ofthe antenna element 174.
  • Other embodiments may include slanted ridges 179 or rounded ridges 181, as illustrated in Figure 12 A.
  • Figure 12B illustrates an antenna element 182 with a top portion 184, a middle portion 186 and a bottom portion 188.
  • a larger surface area for the top portion 184 is achieved through a ridged configuration.
  • the top portion 184 is provided with a plurality of block ridges to maintain the electric field strength between the top portion 184 and the middle portion 186 while reducing the footprint ofthe antenna element 182.
  • FIG. 12C illustrates an antenna element 190 with a top portion 192, a middle portion 194 and a bottom portion 196.
  • both the top portion 192 and the middle portion 194 are provided with a ridged configuration, resulting a larger surface area for each.
  • the ridged configurations allow the antenna element 190 to maintain the electric field strength between the top portion 192 and the middle portion 194 while reducing the footprint ofthe antenna element 182. Configuring both the top portion 192 and the middle portion 194 with ridges allows for an increased reduction in the footprint.
  • Figure 12D illustrates an antenna element 198 with a top portion 200, a middle portion 202 and a bottom portion 204.
  • both the top portion 192 and the middle portion 194 are provided with parallel ridges.
  • the top portion 200 and the middle portion 202 track each other, maintaining a constant gap size between them.
  • the ridged configurations allow the antenna element 198 to maintain the electric field strength between the top portion 200 and the middle portion 202 while reducing the footprint ofthe antenna element 198.
  • FIGS 13A-13D illustrate further embodiments of antenna elements in accordance with the present invention.
  • the illustrated embodiments provide improved isolation by at least partially shielding the bottom plate ofthe antenna elements from a grounding plane and modifying the inductance component ofthe antenna elements.
  • FIG. 13A illustrates an antemia element 206 with a top portion 208, a middle portion 210 and a bottom portion 212.
  • the antenna element 206 is positioned atop a ground plane 214 and is grounded through a ground pad 216.
  • the bottom portion 212 ofthe antenna element 206 is contoured to accommodate a shield 218 between the ground plane 214 and a portion ofthe bottom portion 212.
  • the bottom portion 212 is provided with a raised left side, allowing the shield 218 to be positioned from approximately the middle ofthe bottom portion 212 and extended leftward. The positioning ofthe shield 218 improves the isolation ofthe antenna element 206, thereby improving performance.
  • Figure 13B illustrates an antenna element 220 with a top portion 222, a middle portion 224 and a bottom portion 226.
  • the antenna element 220 is positioned atop a ground plane 228 and is grounded through a ground pad 230.
  • the bottom portion 226 ofthe antenna element 220 is contoured to accommodate a shield 232 between the ground plane 228 and a portion ofthe bottom portion 226.
  • the bottom portion 226 is provided with a raised central region, allowing the shield 232 to be positioned between the central region ofthe bottom portion 226 and the ground plane 228.
  • FIG. 13C illustrates an antenna element 234 with a top portion 236, a middle portion 238 and a bottom portion 240.
  • the antenna element 234 is positioned atop a ground plane 242 and is grounded through an extended ground pad 246.
  • the bottom portion 240 of the antenna element 234 is entirely raised above the ground plane 242.
  • a shield 248 is positioned between the bottom portion 240 and the ground plane 242 to provide improved shielding ofthe antenna element 234.
  • the shield 248 extends substantially the entire length ofthe bottom portion 240, but does not extend beyond the bottom portion 240.
  • Figure 13D illustrates an antenna element 250 with a top portion 252, a middle portion 254 and a bottom portion 256.
  • the antemia element 250 is positioned atop a ground plane 258 and is grounded through an extended ground pad 260.
  • the bottom portion 256 of the antenna element 250 is entirely raised above the ground plane 258.
  • a shield 262 is positioned between the bottom portion 256 and the ground plane 258 to provide improved shielding ofthe antenna element 250.
  • the shield 248 extends beyond one side ofthe bottom portion 240 to provide improved isolation ofthe antenna element 250.
  • FIG 14 illustrates another embodiment of an antenna element arrangement in accordance with the present invention, hi the illustrated arrangement 264, a planar CLMD antenna element 266 is positioned in the same plane as a ground plane 268.
  • a line 270 such as a micro-strip line or a coplanar waveguide, for example, is provided to feed power to the antenna element 266.
  • the antenna element 266 is grounded through a ground pad 272 to the ground plane 268.
  • FIG. 15A illustrates another embodiment of an antenna element arrangement for achieving a very low profile and improved efficiency and isolation.
  • a planar CLMD antenna element 276 is positioned in the same plane as a ground plane 278.
  • a line 280 such as a micro-strip line or a coplanar waveguide, for example, is provided to feed power to the antenna element 276.
  • the antenna element 276 is grounded to the ground plane 268 through a pair of ground pads 282 for improved grounding.
  • FIG 15B illustrates yet another embodiment of an antenna element arrangement for achieving a very low profile and improved efficiency and isolation.
  • a planar CLMD antenna element 286 is positioned in the same plane as a ground plane 288.
  • the ground plane 288 is provided with a cutout 290 that is sufficiently large to accommodate the antenna element 286 therein.
  • the antenna element 286 is surrounded on three sides by the ground plane. Positioning the antenna element 286 in this configuration provides improved isolation.
  • the antenna element 286 is grounded to the ground plane 288 through a pair of ground pads 292.
  • Figures 16A and 16B illustrate further embodiments of antenna element arrangements in accordance with the present invention. In these embodiments, multiple antenna elements may be provided in a single, low-profile arrangement.
  • FIG. 16A illustrates an antenna element arrangement 294 having a ground plane 306.
  • the ground plane 306 is provided with a plurality of cutouts 296, 298.
  • the ground plane 306 is provided with two cutouts 296, 298 positioned in two comers ofthe rectangular ground plane 306.
  • any number of cutouts may be provided, and the cutouts may be positioned at locations other than corners.
  • the arrangement 294 also includes a plurality of CLMD antenna elements 300, 302.
  • the antenna elements 300, 302 are positioned in a coplanar manner with the ground plane 306 and within the cutouts 296, 298, respectively. This configuration improves the isolation ofthe antenna elements 300, 302 and results in a low-profile arrangement.
  • Each antenna element 300, 302 is grounded to the ground plane 306 through ground pads 304 and is provided with power through feed lines 308.
  • the illustrated arrangement 294 results in a low profile and improved isolation.
  • Providing multiple antenna elements, such as antenna elements 300, 302 provides the arrangement with increased diversity.
  • the antenna elements 300, 302 are positioned in a mirrored configuration with the bottom portion of each being faced toward the bottom portion ofthe other.
  • FIG. 16B illustrates another embodiment of an antenna element arrangement for providing low profile, improved isolation and larger bandwidth.
  • the illustrated arrangement 310 is provided with a ground plane 312 having a plurality of cutouts 314, 316.
  • the arrangement 310 also includes a plurality of CLMD antenna elements 318, 320, positioned in a coplanar manner with the ground plane 312 and within the cutouts 314, 316, respectively.
  • Each antenna element 318, 320 is grounded to the ground plane 312 through ground pads 322.
  • the antenna elements 318, 320 are positioned in a mirrored configuration about a center axis ofthe ground plane 312 with a side of each facing a side ofthe other.
  • the antenna elements maybe positioned in various configurations, including positioning the antenna elements orthogonal to each other or at various angles.
  • FIG 17 illustrates another embodiment of an antenna element arrangement in accordance with the present invention.
  • a CLMD antenna element 326 is positioned in a coplanar manner with a ground plane 328 to provide a low profile.
  • the antenna element 326 includes a top portion 330, a middle portion 332 and a bottom portion 334.
  • a component 336 is positioned in the region between the middle portion 332 and the bottom portion 334.
  • the component may be any component such as electrical components including passive and active components such as capacitors, resistors and chipsets.
  • the component may be positioned between the top plate 330 and the middle plate 332.
  • more than one component may be positioned within the antenna element. In this manner, the footprint ofthe antenna element may be used to accommodate the components, thereby conserving valuable space in small devices.
  • Figures 18a-b illustrate respective three-dimensional and side views of one embodiments of a capacitively loaded magnetic dipole antenna 599.
  • antenna 599 comprises a first 501, a second 502, and a third 503 portion.
  • the first portion 501 is coupled to the third portion 503 by a first coupling portion 511
  • the third portion 503 is coupled to second portion 502 by a second coupling portion 512.
  • antenna 599 comprises a feed area, generally indicated as feed area 509, where input or output signals are provided by a feed line 508 that is coupled to the third portion 503.
  • first coupling portion 511 and the second coupling portion 512 are disposed relative to each other in a generally parallel relationship
  • first portion 501, second portion 502, and third portion 503 are disposed relative to each other in a generally parallel relationship.
  • first portion 501, second portion 502, and third portion 503 are disposed relative to each other in a generally coplanar relationship
  • the portions 501, 502, and 503 are generally orthogonal to portions 511 and 512.
  • one or more of portions 501, 502, 503, 511, 512 are disposed in a generally orthogonal or parallel relationship relative to a grounding plane 506.
  • portions 501, 502, 503, 511, 512 may be disposed relative to each other and/or grounding plane 506 in other geometrical relationships and with other geometries.
  • first portion 501 may be coupled to third portion 503, and third portion 503 may be coupled to second portion 502 by respective coupling portions 511 and 512 such that one or more ofthe portions are disposed relative to each other in non-parallel, non-orthogonal, and/or non-coplanar relationships.
  • portions 501, 502, 503, 511, and 512 may comprise conductors.
  • the conductors may be shaped to comprise one or more geometry, for example, cylindrical, planar, etc., or other geometries known to those skilled in the art.
  • the conductors may be flexible, rigid, or a combination thereof.
  • third portion 503 is disposed coplanarly with, or above, grounding plane 506. In one embodiment, third portion 503 is electrically isolated from grounding plane 506, other than where third portion 503 is coupled to grounding plane 506 at the grounding point 507. [0148] It is identified that third portion 503 may include one or more portion that is shaped to comprise other geometries, for example, a linear geometry, a curved geometry, a combination thereof, etc.
  • antenna 599 may be modeled as a radiative resonant LC circuit with a capacitance (C) that corresponds to a fringing capacitance that exists across a first void that is bounded generally by first portion 501 and second portion 502, and which is indicated generally as capacitive area 504; and with an inductance (L) that corresponds to an inductance that exists in a second void that is bounded generally by the second portion 502 and third portion 503, and which is indicated generally as inductive area 505.
  • C capacitance
  • L inductance
  • portions 501, 502, 503, 511, 512, and the gaps formed thereby may be used to effectuate an operating frequency about which the antenna 599 resonates to radiate or receive a signal.
  • FIG. 18C illustrates a three-dimensional view of an embodiment of a capacitively loaded magnetic dipole antenna 598.
  • Some aspects of antenna 598 are similar to embodiments of antenna 599 described previously above and may be understood by those skilled in the art by referring to the description of antenna 599. However, it is identified that at least one aspect of antenna 598 differs from that of antenna 599.
  • third portion 53 is defined by a length that is longer than a straight-line distance (c) between a first end (a) and a second end (b) of the third portion.
  • third portion 503 includes linear portions that are coupled in alternating orthogonal orientations.
  • third portion 503 may include one or more portion that comprises or is coupled to comprise other geometries, for example, a linear geometry, a curved geometry, a combination thereof, etc.
  • portion 501, portion 502, and portion 503 are coupled to a substrate 515.
  • substrate 515 comprises a high dissipation factor substrate, for example, a FR4 substrate known by those skilled in the art.
  • substrate 515 is defined by an outer periphery 516 and by an inner periphery 517, and the inner periphery defines a void within the substrate.
  • the capacitive area 504 generally spans the void.
  • an antenna 598 that has an equivalent capacitance may be provided to comprise a smaller form-factor/profile, for example, as measured in a direction orthogonal to grounding plane 506.
  • the antenna 598 inductance in the inductive area 505 may be increased over that ofthe inductance ofthe antenna 599.
  • an antenna 598 that has an equivalent inductance may be provided to comprise a smaller form- factor/profile, for example, as measured in a direction orthogonal to grounding plane 506.
  • FIG 19 illustrates a three-dimensional view of a capacitively loaded magnetic dipole antenna 597.
  • antenna 597 comprises a first 501, a second 502, and a third 503 portion. It is identified that antenna 597 may be modeled as a radiative resonant LC circuit with a capacitance (C) that corresponds to a fringing capacitance that exists in a capacitive area 504 that is bounded generally by first portion 501 and second portion 502; and with an inductance (L) that corresponds to an inductance that exists in an inductive area 505 that is bounded generally by the second portion 502 and the third portion 503.
  • C capacitance
  • L inductance
  • the first portion 501 is coupled to the third portion 503 by a first coupling portion 511
  • the third portion 503 is coupled to a second portion 502 by a second coupling portion 512
  • antenna 598 comprises a feed line 508 coupled to the third portion 503 where input or output signals are provided.
  • third portion 503 is defined by a length that is longer than a straight-line distance (c) between a first end (a) and a second end (b) ofthe third portion.
  • Figure 19a also illustrates an embodiment of antenna 598 wherein third portion 503 is disposed in a generally non-coplanar relationship relative to the generally coplanar relationship ofthe first portion 501 and second portion 502.
  • third portion 503 may be disposed in a plane that his generally coplanar with, or above, a grounding plane 506. In one embodiment, third portion 503 may be electrically isolated from the grounding plane 506 other than where third portion 503 is coupled to grounding plane 506 at grounding point 507. It is identified that third portion 503 may include one or more portion that comprises or is coupled to comprise other geometries, for example, a linear geometry, a curved geometry, a combination thereof, etc.
  • the grounding plane 506 and/or one or more portion of third portion 503 may be disposed in a plane that is generally orthogonal to a coplanar relationship ofthe first portion 501 and the second portion 502. h one embodiment (not illustrated), the grounding plane 506 and/or one or more portion of third portion 503 may be disposed in a plane that is in a generally angular relationship relative to a substrate 515, which first portion 501 and second portion 502 are coupled to. In one embodiment, the angular relationship of third portion relative to substrate 515 may be between 0 and 180 degrees.
  • substrate 515 comprises a high dissipation factor substrate, for example, a FR4 substrate.
  • substrate 515 is defined by an outer periphery 516 and by an inner periphery 517, and the inner periphery defines a void within the substrate. In one embodiment, the capacitive area 504 spans the void.
  • the capacitance of antenna 597 may be increased over that ofthe capacitance of antenna 599.
  • an antenna 597 that has an equivalent capacitance may be provided to comprise a smaller form-factor/profile.
  • the antenna 597 inductance in the inductive area 505 may be increased over that ofthe inductance of antenna 599.
  • an antenna 597 that has an equivalent capacitance may be provided to comprise a smaller form- factor/profile.
  • the antenna 597 inductance in the inductive area 505 may be increased over that ofthe inductance of antenna 599.
  • an antenna 597 that has an equivalent inductance may be provided to comprise a smaller form- factor/profile.
  • Figures 20a-b illustrate three-dimensional views of embodiments of an capacitively loaded magnetic dipole antenna 596 and 595.
  • the first portion 501 is coupled to the third portion 503 by a first coupling portion 511
  • the third portion 503 is coupled to second portion 502 by a second coupling portion 512.
  • antenna 596 comprises a feline 508 coupled to the third portion 503 where input or output signals are provided
  • third portion 503 is defined by a length that is longer than a straight-line distance (c) between a first end (a) and a second end (b) ofthe third portion.
  • Figures 20a and 20b also illustrate embodiments wherein at least one portion ofthe third portion 503 is disposed in a generally coplanar relationship relative to the generally coplanar relationship ofthe first portion 501 and second portion 592.
  • third portion 503 may include one or more portion that comprises or is coupled to comprise other geometries, for example, a linear geometry, a curved geometry, a combination thereof, etc.
  • Figures 20a-b also illustrate embodiments wherein at least one portion of third portion 503 may be disposed in a plane that is generally coplanar with, or above, a grounding plane 506.
  • third portion 593 is electrically isolated from the grounding plane 506 other than where third portion 503 is coupled to grounding plane 506 at a grounding point 507.
  • the grounding plane 506 and/or at least a portion of third portion 503 may be disposed in a plane that is in an angular relationship relative to a coplanar relationship of first portion 501 and second portion 502. In one embodiment, the angular relationship relative to substrate 515 and may be between 0 and 180 degrees.
  • substrate 515 comprises a high dissipation factor substrate, for example, a FR4 substrate. In one embodiment, substrate 515 is defined by an outer periphery 516 and by an inner periphery 517, and the inner periphery defines a void within the substrate. In one embodiment, the capacitive area 504 generally spans the void.
  • the capacitance of antennas 596 and 595 may be increased over that ofthe capacitance of antenna 599.
  • an antenna 596 and 595 that has an equivalent capacitance may be provided to comprise a lower form-factor/profile.
  • the inductance of antenna 596 and 595 that has an equivalent inductance may be provided to comprise a lower form-factor/profile.
  • Figure 23 illusfrates a single-mode capacitively loaded antenna. If we assume that the structure in Figure 23 can be modeled as a Li circuit, then Ci is the capacitance across gap g. Inductance Li is mainly contributed by the loop designated by the numeral 702. The gap g is much smaller than the overall thickness ofthe antenna. The presence of only one LC circuit limits this antenna design to operating at a single frequency.
  • Figure 24 illustrates a dual-mode antenna based on the same principles as the antenna shown in Figure 23.
  • a second antenna element is placed inside the first antenna element described above. This allows tuning one to a certain frequency ft and the other one to another frequency f 2 .
  • the two antennas have a common ground, but different capacitive and inductive elements.
  • Figure 25 illusfrates a multimode antenna with shared inductances L] and L 2 . and discrete capacitances , C 2 , and C .
  • the antenna comprises several antenna elements.
  • One embodiment ofthe present invention relates to an antenna with the radiating elements and the conductor lying in substantially the same plane.
  • the radiating elements and the planar element have a thickness that is much less then either their length or width; thus they are essentially two dimensional in nature.
  • the antenna structure is affixed to a substrate.
  • Figure 26 illustrates an antenna 10 in accordance with the principles ofthe present invention that is formed flat on a subsfrate 712.
  • the antenna is substantially two-dimensional in nature.
  • the antenna comprises a planar conductor 714, a first parallel elongated conductor 716, and a second parallel elongated conductor 718.
  • the planar conductor is positioned in the same plane as the electric field, known as the E-plane.
  • the E-plane of a linearly polarized antenna contains the electric field vector ofthe antenna and the direction of maximum radiation.
  • the E-plane is orthogonal to the H-plane, i.e. the plane containing the magnetic field.
  • the H-plane contains the magnetic field vector and the direction of maximum radiation.
  • Each of elongated conductors 716 and 718 are electrically connected to the planar conductor 714 by respective connecting conductors 720 and 722.
  • Antenna 710 comprises elongated conductors 716 and 718 that are in the same or substantially the same plane as the planar conductor 714.
  • the gap between the elongated conductor 716 and the elongated conductor 718 is the region of capacitance.
  • the gap between the elongated conductor 716 and the planar conductor 714 is the region of inductance.
  • the space between the first elongated conductor 716 and the second elongated conductor 718 is much less than the space between the first elongated conductor 716 and the planar conductor 714.
  • the radiating element and the conductor may be isolated, hi Figure 27, a grounded planar conductor 732 is isolated from a radiating element 730 by an etched area 734.
  • An antenna feed 736 is supplied and a return for the ground 738 is supplied.
  • the antenna feeds 736, or feed lines are fransmission lines of assorted types that are used to route RF power from a transmitter to an antenna, or from an antenna to a receiver.
  • any ofthe antenna structures discussed herein could utilize an etched area or other means to isolate the radiating element or elements.
  • FIG. 28A-28C show an antenna 740 with planar conductors 744 and 746 on opposite sides ofthe substrate 742.
  • Vias 750 and 752 provide the antenna feed and shorts to ground, respectively.
  • the vias 750 and 752 connect the radiating elements to the planar conductor 746.
  • the antenna structure may utilize more than one radiating element.
  • the radiating elements may be arranged side-by-side as showing in Figures 29A- 29C.
  • Figures 29A-29C show a dual frequency antenna structure, similar to the single element structure of Figures 28A-28C
  • the antenna structure has radiating elements 760 and 762 arranged side-by-side. Each radiating element has vias connecting the radiating element to the planar conductor on the opposite face ofthe substrate.
  • the planar conductors are substantially parallel to each other.
  • the radiating structures may be placed in a nested configuration as shown in Figure 30.
  • Figure 30 shows another dual frequency arrangement implementing the design of Figure 24 on a substrate in a manner similar to Figure 26.
  • the antenna structure may utilize three or more radiating elements. The radiating elements may all be located on the same face as the planar conductor.
  • Figure 31 shows an antenna structure similar to that of Figure 30, but with an additional conductor 770 to increase the frequency diversity.
  • Figures 32A-32B show an antenna structure on a substrate 780.
  • Face A of subsfrate 780 carries a three frequency antenna structure as shown in Figure 731.
  • Face B of substrate 780 carries a single frequency antenna structure as shown in Figure 25, although alternatively this could also be a multifrequency structure or any combination of single and multifrequency structures.
  • the antenna structure may comprise conductors on any of the faces ofthe substrate.
  • the conductors may be located in parallel and opposite arrangements or asymmetrically.
  • Figures 33A-33B show an antenna structure 790 with conductors formed, such as by conventional printed circuit methods, on the edges as well as the face surface ofthe substrate 792. This allows even more space savings in certain packaging configurations.
  • more than one substrate may be used.
  • an second substrate bearing additional conductors can be utilized.
  • the second substrate may be located perpendicular to the first subsfrate.
  • a primary substrate 800 carries a multifrequency antemia structure, such as the one shown in Fig. 31.
  • a secondary substrate 802 is mounted substantially perpendicular to the primary substrate.
  • the substrate 802 carries a single frequency antenna structure, although alternatively this too could be a multifrequency structure.
  • FIGS 35A-35B show additional arrangements, similar to Figures 34A-34B, wherein a plurality of secondary substrates, each carrying respective antenna structures, are mounted on a primary substrate.
  • the secondary subsfrate may be arranged in any configuration, not only in perpendicular positions.
  • Figure 36 illustrates an antenna 810 on a substrate 812 that is extended relative to substrate 814. This allows installation ofthe antenna in an enclosure with a shape that just allows an antenna along the side ofthe enclosure.
  • Figure 37 illustrates a configuration similar to that of Figure 36, but with two antennas for frequency diversity.
  • An antenna structure in accordance with the principles of the present invention may be integrated into an electronic device.
  • the previously discussed benefits ofthe present invention make such an antenna structure well suited to use in small electronic devices, for example, but not limited to mobile telephones.
  • Figure 38 shows the antenna structure of Figure 37 housed within an enclosure, such as the case of a mobile telephone or other electronic device.
  • Figure 39 illustrates a configuration similar to that of Figure 37, but with four radiating elements, including elements carried on secondary substrates 820 and 822.
  • Figure 40 shows the antenna structure of Figure 39 housed within an enclosure, such as the case of a mobile telephone or other electronic device.
  • the low profile ofthe antenna ofthe present invention allows for the antenna to be placed easily within electronic devices without requiring «a specifically dedicated volume.
  • Figure 41 illustrates a circuit board 130 with radiating elements 832 and 834 disposed at opposite ends thereof.
  • an electronic device such as a laptop computer 840, is configured with a plurality of radiating elements. Owing to their construction, the radiating elements may be arranged within the computer wherever space is available. Thus, the design ofthe computer housing need not be dictated by the antenna requirements.
  • the antenna structure may comprise grooves.
  • the grooves may be partially or completely through the substrate in various locations, such as between the radiating elements.
  • Figure 43 illustrates an antenna ofthe type generally shown in Figure 27.
  • the antenna is formed, such as by conventional printed circuit techniques, on a substrate 850.
  • a groove 852 is milled partially or completely through the substrate in the capacitive region ofthe antenna to improve the efficiency ofthe antenna.
  • Figure 44 illusfrates the same concept shown in Figure 43, but in the case of a multifrequency antenna.
  • a plurality of grooves 862 are milled into substrate 860 between each pair of radiating conductors.
  • FIG. 45 illustrates an alternative method for fabricating an antenna in accordance with the present invention. Rather than etching the antenna pattern on a printed circuit board, here the antenna is etched on a metallic film that is then molded in plastic. The resulting structure may be attached in various ways to a circuit board or to a device enclosure.

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Abstract

The disclosed embodiments of antenna elements (10, 28, 38) and antenna element arrangements provide a generally low profile, improved isolation, and providing a larger bandwidth. Certain disclosed antenna elements provide a reduction in the footprint of the antenna elements while maintaining the performance characteristics by providing a greater surface area on either a top, middle or bottom portion of a CLMD antenna. Other disclosed antenna element arrangements provide improved radiation efficiency by providing metallic reflectors (92, 94) on the sides of antenna elements. The isolation characteristics of certain disclosed antenna elements are improved through the use of coplanar wave guides (104). The bandwidth may be improved through the use of stubs resonators (116). The bandwidth of the antenna elements may be improved without reducing isolation or shielding by providing a variable gap (d) between two portions of the antenna elements.

Description

ANTENNASWITHREDUCED SPACEAND IMPROVED
PERFORMANCE
FIELD OF THE INVENTION
[0001] The present invention relates generally to the field of wireless communications, and particularly to the size reduction and performance improvement of capacitively loaded magnetic dipole antennas.
BACKGROUND OF THE INVENTION [0002] An antenna is an electrical conductor or array of conductors that radiates (transmits and/or receives) electromagnetic waves. A magnetic dipole antenna is a loop antenna that radiates electromagnetic waves in response to current circulating through the loop. Electromagnetic waves are often referred to as radio waves. Most antennas are resonant devices, which operate efficiently over a relatively narrow frequency band. An antenna must be tuned to the same frequency band that the system using it operates in, otherwise reception and/or transmission will be impaired.
[0003] The bandwidth of an antenna refers to the range of frequencies over which the antenna can operate satisfactorily. It is usually defined by impedance mismatch but it can also be defined by pattern features such as gain, beamwidth, etc.. Antenna designers quickly assess the feasibility of an antenna requirement by expressing the required bandwidth as a percentage ofthe center frequency ofthe band. Different types of antennas have different bandwidth limitations. Normally, a fairly large volume is required if a large bandwidth is desired. Accordingly, the present invention addresses the needs of small compact antenna with wide bandwidth. The present invention provides a versatile antenna design that resonates at more than one frequency, that is it is multiresonant, and that may be adapted to a variety of packaging configurations. [0004] The antenna contains one or more elements. Elements are the conductive parts of an antenna system that determine the antenna's electromagnetic characteristics. The element of an magnetic dipole antenna is designed so that it resonates at a predetermined frequency as required by the application for which it is being used. The antenna's resonant frequency is dependant on the capactive and inductive properties ofthe antenna elements. The capacitive and inductive properties ofthe antenna elements are dictated by the dimensions ofthe antenna elements and their interrelations.
[0005] The radiated electromagnetic wave from an antemia is characterized by the complex vector E x H in which E is the electric field and H is the magnetic field. Polarization describes the orientation ofthe radiated wave's electric field. For maximum performance, polarization must be matched to the orientation ofthe radiated field to receive the maximum field intensity ofthe electromagnetic wave. If it is not oriented properly, a portion ofthe signal is lost, known as polarization loss.
[0006] Dependent on the antenna type, it is possible to radiate linear, elliptical, and circular signals. In linear polarization the electric field vector lies on a straight line that is either vertical (vertical polarization), horizontal (horizontal polarization) or on a 45 degree angle (slant polarization). If the radiating elements are dipoles, the polarization simply refers to how the elements are oriented or positioned. If the radiating elements are vertical, then the antenna has vertical polarization and if horizontal, it has horizontal polarization. In circular polarization two orthogonal linearly polarized waves of equal amplitude and 90 degrees out of phase are radiated simultaneously.
[0007] Magnetic dipole antennas can be designed with more than one antenna element. It is often desirable for an antenna to resonate at more than one frequency. For each desired frequency, an antenna element will be required. Different successive resonances occur at the frequencies fi, f2, £... fn. These peaks correspond to the different electromagnetic modes excited inside the structure. The antenna can be designed so that the frequencies provide the antenna with a wide bandwidth of coverage by utilizing overlapping or nearly overlapping frequencies. However, antennas that have an wider bandwidth than a monoresonant antenna often have a correspondingly increased size.
[0008] Small antennas are desired for use in and with portable wireless communication devices. With classical antenna structures, a certain physical volume is required to produce a resonant antenna structure at a particular radio frequency and with a particular bandwidth. Thus, traditionally bandwidth and frequency requirements dictated the volume of an antenna, and therefore to some extent placed limitations upon the design of wireless devices. Many present day applications require that antennas provide large bandwidth, efficiency, and isolation in as small form factor as possible.
[0009] Thus, there is a need in the art for a multiresonant antenna; wherein the individual antenna elements share volume within the antenna structure.
SUMMARY OF THE INVENTION [0010] The present invention includes antenna elements and antenna element arrangements having a generally low profile, improved isolation, and a large bandwidth in comparison to prior art antennas. In one aspect of the present invention, the antenna elements include both capacitive and inductive parts. Each element provides a frequency or band of frequencies to the antenna. The preferred embodiments relate to a capacitively loaded magnetic dipole
(CLMD) antenna having antenna elements having improved grounding characteristics to improve isolation. Other embodiments provide a reduction in the footprint ofthe antenna elements while maintaining the performance characteristics by providing a greater surface area on either a top, middle or bottom portion of a CLMD antenna. [0011] Further embodiments provide antenna element arrangements with improved radiation efficiency by providing metallic reflectors on the sides of antenna elements. In still other embodiments, the isolation characteristics of antenna elements are improved through the use of coplanar wave guides. The bandwidth may be improved through the use of stubs resonators. In yet further embodiments, the bandwidth ofthe antenna elements is improved without reducing isolation or shielding by providing a variable gap between two portions of the antenna elements.
[0012] In other embodiments, shielding ofthe antenna element is improved by providing a shield between at least a portion ofthe antenna element and a ground plane. In additional embodiments, a lower profile is achieved by positioning the antenna elements in a coplanar manner with a ground plane. In further embodiments, the isolation ofthe antenna element is improved by positioning the antenna element in a cutout provided in the ground plane. In still further embodiments, the antenna element arrangement may achieve a larger bandwidth by positioning two or more antenna elements in a plurality of cutouts in the ground plane. Further, a savings in volume may be achieved by positioning other components within the footprint ofthe antenna element.
[0013] The present invention includes a wireless device comprising: a first portion; a second portion, the first and second portion disposed to effectuate a capacitive area; and a third portion, the third portion coupled to the first portion and to the second portion to effectuate an inductive area, wherein the third portion comprises a length having a first end and a second end, wherein the length is longer than a straight line distance between the first end and the second end, and wherein the first portion, the second portion, and the third portion define a capacitively coupled dipole antenna.
[0014] The present invention includes a dipole antenna comprising: a first portion; a second portion, the first and second portion disposed to create a capacitive area; and a third portion, the third portion comprising one or more portion, the third portion coupled to the first portion and to the second portion to create an inductive area, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end. One or more portion ofthe third portion may be disposed relative to the first portion and the second portion in a non- parallel relationship. One or more portion ofthe third portion may be disposed relative to the first portion and the second portion in a parallel relationship. The first and second portion may be disposed in a generally coplanar relationship, and one or more portion ofthe third portion may be disposed in a plane that is in an angular relationship relative to the coplanar relationship ofthe first and second portion. The first portion, the second portion, and the third portion may be disposed on or above a ground plane. The antenna may include a substrate, wherein the first portion and the second portion are coupled to the substrate. The antenna may include a FR4 substrate. The FR4 substrate may be defined by a periphery, wherein within the periphery the FR4 substrate defines a void, and wherein the capacitive area generally spans the void. The first portion, the second portion, and the third portion may be coupled to crate a capacitively coupled dipole antenna.
[0015] The present invention includes a system, comprising: a dipole antenna including, a first portion; a second portion, the first and second portion disposed in a relationship to create a capacitive area; and a third portion, the third portion coupled to the first portion and to the second portion and disposed to create an inductive area, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end. The antenna may further include a high dissipation factor substrate. The antenna may include an FR4 substrate. The first and second portion may be coupled to the FR4 substrate, wherein the FR4 substrate is defined by a periphery, wherein within the periphery the FR4 substrate defines a void, and wherein the capacitive area generally spans the void. The system may comprise a wireless communications device.
[0016] The present invention includes a capacitively couple dipole antenna, comprising: capacitance means for creating a capacitance; and inductive means for creating an inductance. The antenna may comprise a first portion, a second portion, and a third portion, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end. The antenna may comprise a substrate. The first and second portion may be coupled to the substrate, wherein the substrate is defined by a periphery, wherein within the periphery the substrate defines a void, wherein the capacitance generally spans the void.
[0017] The present invention includes a method for creating a resonance in a resonant circuit comprising the steps of: providing a first portion; providing a second portion; disposing the first and second portion to crate a capacitive area; and providing a third portion, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end; and coupling the third portion to the first portion and to the second portion to create an inductive area. The method may further include the step of: providing a high dissipation factor substrate, wherein the high dissipation factor substrate is defined by a periphery, wherein within the periphery the high dissipation factor substrate defines a void, and wherein the capacitive area generally spans the void.
[0018] hi a preferred embodiment, the basic antenna element comprises a substantially planar structure with a planar conductor and a pair of parallel elongated conductors, each having a first end electrically connected to the planar conductor. Additional elements may be coupled to the basic element in an array. In this way, individual antenna structures share common elements and volumes, thereby increasing the ratio of relative bandwidth to volume. [0019] Other embodiments and other features will become apparent by referring to the Description and the Claims that follow. This summary does not purport to define the invention. The invention is defined by the claims.
BRIEF DESCRIPTION. OF THE DRAWINGS
[0020] Figure 1 conceptually illustrates the antenna designs ofthe present invention.
[0021] Figure 2 illustrates the increased overall bandwidth achieved with a multiresonant antenna design.
[0022] Figure 3 is an equivalent circuit for a radiating structure.
[0023] Figure 4 is an equivalent circuit for a multiresonant antenna structure.
[0024] Figure 5 A illustrates a three-dimensional view of an embodiment of an antenna element;
[0025] Figure 5B illustrates a side-view ofthe antenna element illustrated in Figure 5 A;
[0026] Figure 6A illustrates a side-view of an embodiment of antenna element in accordance with the present invention;
[0027] Figure 6B illustrates a side-view of another embodiment of antenna element in accordance with the present invention;
[0028] Figure 6C illustrates a side-view of yet another embodiment of antenna element in accordance with the present invention;
[0029] Figure 7A illustrates a side-view of another embodiment of an antenna element in accordance with the present invention;
[0030] Figure 7B illustrates a side-view of various embodiments ofthe bottom portion of the antenna element illustrated in Figure 3 A;
[0031] Figure 7C illustrates a side-view of another embodiment of an antenna element in accordance with the present invention;
[0032] Figure 7D illustrates a side-view of various embodiments ofthe bottom portion of the antenna element illustrated in Figure 3C; [0033] Figure 7E illustrates a side-view of another embodiment of an antenna element in accordance with the present invention;
[0034] Figure 7F illustrates a side-view of various embodiments ofthe bottom portion of the antenna element illustrated in Figure 3E;
[0035] Figure 8 A illustrates a three-dimensional view of an embodiment of an antenna element arrangement in accordance with the present invention;
[0036] Figure 8B illustrates a side-view ofthe antenna element arrangement illustrated in Figure 4A;
[0037] Figure 8C illustrates a top- view ofthe antenna element arrangement illustrated in Figures 4 A and 4B;
[0038] Figure 9A illustrates a top-view of an embodiment of an antenna element arrangement in accordance with the present invention;
[0039] Figure 9B illustrates a radio frequency (RF) schematic ofthe antenna element arrangement of Figure 5 A;
[0040] Figure 9C illustrates a top- view of another embodiment of an antenna element arrangement in accordance with the present invention;
[0041] Figure 9D illustrates a radio frequency (RF) schematic ofthe antenna element arrangement of Figure 5C;
[0042] Figure 9E illustrates a top-view of another embodiment of an antenna element arrangement in accordance with the present invention;
[0043] Figure 9F illustrates an embodiment of a radio frequency (RF) schematic ofthe antenna element arrangement of Figure 5E;
[0044] Figure 9G illustrates another embodiment of a radio frequency (RF) schematic of the antenna element arrangement of Figure 5E;
[0045] Figure 9H illustrates yet another embodiment of a radio frequency (RF) schematic ofthe antenna element arrangement of Figure 5E;
[0046] Figure 10A illustrates a side-view of an embodiment of an antenna element;
[0047] Figures 10B and 6C illustrate cross-sectional views taken along VIB-NIB ofthe antenna element illustrated in Figure 10 A; [0048] Figure 10D illustrates a side-view of an embodiment of an antenna element in accordance with the present invention;
[0049] Figure 11 A illustrates a side-view of another embodiment of an antenna element in accordance with the present invention;
[0050] Figure 1 IB illustrates a side-view of still another embodiment of an antenna element in accordance with the present invention;
[0051] Figure 11C illustrates a side-view of yet another embodiment of an antenna element in accordance with the present invention;
[0052] Figure 12A illustrates a side-view of an embodiment of an antenna element in accordance with the present invention;
[0053] Figure 12B illustrates a side-view of another embodiment of an antenna element in accordance with the present invention;
[0054] Figure 12C illustrates a side-view of yet another embodiment of an antenna element in accordance with the present invention;
[0055] Figure 12D illustrates a side-view of still another embodiment of an antenna element in accordance with the present invention;
[0056] Figure 13 A illustrates a side-view of an embodiment of an antenna element arrangement in accordance with the present invention;
[0057] Figure 13B illustrates a side-view of another embodiment of an antenna element arrangement in accordance with the present invention;
[0058] Figure 13C illustrates a side-view of still another embodiment of an antenna element arrangement in accordance with the present invention;
59] Figure 13D illustrates a side-view of yet another embodiment of an antenna element arrangement in accordance with the present invention;
[0060] Figure 14 illustrates a three-dimensional view of an embodiment of an antenna element arrangement in accordance with the present invention;
[0061] Figure 15 A illustrates a top view of an embodiment of an antenna element arrangement in accordance with the present invention; [0062] Figure 15B illustrates a top view of another embodiment of an antenna element arrangement in accordance with the present invention;
[0063] Figure 16A illustrates a top view of an embodiment of an antenna element arrangement in accordance with the present invention;
[0064] Figure 16B illustrates a top view of another embodiment of an antenna element arrangement in accordance with the present invention; and
[0065] Figure 17 illustrates a top view of still another embodiment of an antenna element arrangement in accordance with the present invention.
[0066] Figures 18 A-B illustrate a respective three-dimensional and side view of a capacitively loaded dipole antenna.
[0067] Figure 18C illustrates a three dimensional view of a low profile/small form factor capacitively loaded dipole antenna.
[0068] Figure 19 illustrates a three dimensional view of a low profile/small form factor capacitively loaded dipole antenna.
[0069] Figures 20A-B illustrate three dimensional views of a low profile/small form factor capacitively loaded dipole antenna.
[0070] Figure 21 illustrates a low profile/small form factor antenna in accordance with the principles ofthe present invention.
[0071] Figure 22 illustrates two low profile/small form factor antennas in accordance with the principles ofthe present invention coupled together.
[0072] Figure 23 illustrates a basic radiating structure utilized in an embodiment ofthe present invention.
[0073] Figure 24 illustrates a dual-mode antenna in accordance with an embodiment ofthe present invention.
[0074] Figure 25 illustrates a multimode antenna in accordance with another embodiment ofthe present invention.
[0075] Figure 26 illustrates an antenna in accordance with the present invention that is formed flat on a substrate. [0076] Figure 27 illustrates an antenna in accordance with an embodiment ofthe present invention with returns for ground and a feed.
[0077] Figures 28A-C illustrate the use of vias to provide feeds and shorts for an antenna in accordance with an embodiment ofthe present invention.
[0078] Figures 29A-C illustrate a dual frequency antenna in accordance with an embodiment ofthe present invention with side-by-side elements.
[0079] Figure 30 illustrates a dual frequency antenna in accordance with an embodiment of the present invention with nested elements.
[0080] Figure 31 illustrates an antenna in accordance with an embodiment ofthe present invention similar to that of Fig. 30 with an additional capacitive element to provide an additional resonant frequency.
[0081] Figures 32A-B illustrate a two-sided antenna in accordance with an embodiment of the present invention with three frequencies on one face of a substrate and a single frequency on the other face.
[0082] Figures 33 A-B illustrate an antenna in accordance with an embodiment ofthe present invention with conductors formed on the edge as well as the face of a substrate.
[0083] Figures 34 A-B illustrate a multifrequency planar antenna in accordance with an embodiment ofthe present invention on a primary substrate with an additional radiating element on a perpendicular secondary substrate.
[0084] Figures 35A-B illustrate antennas in accordance with an embodiment ofthe present invention with multiple secondary substrates.
[0085] Figure 36 illustrates an antenna in accordance with an embodiment ofthe present invention with an extended radiating element.
[0086] Figure 37 illustrates an antenna in accordance with an embodiment ofthe present invention with a pair of extended radiating elements.
[0087] Figure 38 shows the antenna of Fig. 37 within an enclosure in accordance with an embodiment ofthe present invention.
[0088] Figure 39 illustrates an antenna similar to that of Fig. 37 with additional radiating elements on perpendicular secondary substrates in accordance with an embodiment ofthe present invention. [0089] Figure 40 shows the antenna of Fig. 39 within an enclosure in accordance with an embodiment ofthe present invention.
[0090] Figure 41 illustrates an antenna structure in accordance with an embodiment ofthe present invention with two radiating elements at opposite ends of a substrate.
[0091] Figure 42 illustrates a laptop computer in accordance with an embodiment ofthe present invention with multiple radiating elements.
[0092] Figure 43 illustrates an antenna in accordance with an embodiment ofthe present invention printed on a substrate with a milled groove between the conductors.
[0093] Figure 44 illustrates a multifrequency antenna in accordance with an embodiment of the present invention with a plurality of milled grooves.
[0094] Figure 45 illustrates an alternative method of fabricating an antenna structure in accordance with an embodiment ofthe present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0095] The disclosed embodiments ofthe present invention include antenna elements and antenna element arrangements having a generally low profile, improved isolation, and providing a larger bandwidth.
[0096] The volume to bandwidth ratio is one ofthe most important constraints in modern antenna design. The physical volume of an antenna can place severe constraints on the design of small electronic devices. One approach to increasing this ratio is to re-use the volume for different modes. Some designs already use this approach, even though the designs do not optimize the volume to bandwidth ratio. In these designs, two modes are generated using the same physical structure, although the modes do not use exactly the same volume. The current repartition ofthe two modes is different, but both modes nevertheless use a common portion ofthe total available volume ofthe antenna. This concept of utilizing the physical volume ofthe antenna for a plurality of antenna modes is illustrated generally by the Venn Diagram of Figure 1. The physical volume ofthe antenna ("N") has two radiating modes. The physical volume associated with the first mode is designated W, whereas that associated with the second mode is designated V '. It can be seen that a portion ofthe physical volume, designated 'Nιj2', is common to both ofthe modes.
[0097] The concept of volume reuse and its frequency dependence are expressed with reference to "K law". The general K law is defined by the following:
Af / f = K » V/ λ3 [0098] wherein Δf/f is the normalized frequency bandwidth, λ is the wavelength, and the term A represents the physical volume that will enclose the antenna. This volume so far has not been optimized and no discussion has been made on the real definition of this volume and the relation fr the K factor.
[0099] In order to have a better understanding of the K law, different K factors are defined: Kmodai is defined by the mode volume N; and the corresponding mode bandwidth:
where i is the mode index.
Kmodai is thus a constant related to the volume occupied by one electromagnetic mode.
Keffective is defined by the union ofthe mode volumes Ni U N2 U..N; and the cumulative bandwidtr
It can be thought of as a cumulative K:
t Δf/ / f / = /rβΛeΛβ . (v v2 .v/)/ ^ where λ is the wavelength ofthe central frequency.
[0100] Keffective is a constant related to the minimum volume occupied by the different excited modes taking into account the fact that the modes share a part ofthe volume. The different frequencies f; must be very close in order to have nearly overlapping bandwidths.
[0101] Kphysicai or Kobserved is defined by the physical volume 'V ofthe antenna and the overall antenna bandwidth:
Af / f = Kphysical * V/λ3 [0102] Kphysicai or Kobserved is the most important K factor since it takes into account the real physical parameters and the usable bandwidth. Kphysicai is also referred to as Kobserved since it is the only K factor that can be calculated experimentally. In order to have the modes confined within the physical volume ofthe antenna, Kphysicai must be lower than Keffective- However these K factors are often nearly equal. The best and ideal case is obtained when Kphysicai is approximately equal to Keffective and s also approximately equal to the smallest Kmodai- It should be noted that confining the modes inside the antenna is important in order to have a well-isolated antenna.
[0103] One ofthe conclusions from the above calculations is that it is important to have the modes share as much volume as possible in order to have the different modes enclosed in the smallest volume possible. As previously discussed, the concept is illustrated in the Venn Diagram shown in Figure 1. Maximizing the number of modes while minimizing the volume ofthe antenna results in antennas that are multiresonant, yet are not much larger than a monoresonant antenna.
[0104] For a plurality of radiating modes i, Figure 2 shows the observed return loss of a multiresonant structure. Different successive resonances occur at the frequencies fls f2, fj... fn. These peaks correspond to the different electromagnetic modes excited inside the structure. Figure 2 illustrates the relationship between the physical, or observed, K and the bandwidth over ft to fn.
[0105] For a particular radiating mode with a resonant frequency at fi, we can consider the equivalent simplified circuit LiCi shown in Figure 3. By neglecting the resistance in the equivalent circuit, the bandwidth ofthe antenna is simply a function ofthe radiation resistance. The circuit of Figure 3 can be repeated to produce an equivalent circuit for a plurality of resonant frequencies. [0106] Figure 4 illustrates a multimode antenna represented by a plurality of inductance(L)/capacitance(C) circuits. At the frequency ft only the circuit LiCi is resonating. Physically, one part ofthe antenna structure resonates at each frequency within the covered spectrum. By utilizing antenna elements with overlapping resonance frequencies of ft to fn, an antenna in accordance with the present invention can cover frequencies 1 to n. Again, neglecting real resistance ofthe structure, the bandwidth of each mode is a function ofthe radiation resistance.
[0107] As discussed above, in order to optimize the K factor, the antenna volume is reused for the different resonant modes. One embodiment ofthe present invention utilizes a capacitively loaded microstrip type of antenna as the basic radiating structure. Modifications of this basic structure will be subsequently described. In a highly preferred embodiment, the elements ofthe multimode antenna structures have closely spaced resonance frequencies.
[0108] Figures 5A and 5B illustrate an embodiment of a capacitively loaded magnetic dipole (CLMD) antenna in accordance with the principles ofthe present invention. The antenna element 10 includes a top portion 12, a middle portion 14 and a bottom portion 16. Each portion 12, 14, 16 may be a two-dimensional plate or a one-dimensional element. The top portion 12 and the middle portion 14 form a capacitive component 18 ofthe antenna element 10. A loop between the middle portion 14 and the bottom portion 16 forms an inductive component 20 ofthe antenna element 10. The antenna element 10 is connected to a grounding plane 22 by a grounding point 24. A feeding line 26 provides power to the antenna element 10.
[0109] Figure 6A illustrates a side-view of an antenna element 28 similar to the antenna element 10 described above with reference to Figures 5 A and 5B. The antenna element 28 includes a top portion 30, middle portion 32 and bottom portion 34 forming a capacitive component and an inductive component. The embodiment illustrated in Figure 6A provides improved grounding ofthe antenna element 10 to a grounding plane (not shown in Figure 6 A) through an elongated grounding point 36. The elongated grounding point 36 illustrated in Figure 6 A extends from one end ofthe bottom portion 34 inward by a predetermined length. The size ofthe grounding point 36 may be selected for the desired grounding characteristics ofthe antenna element 28. Thus, the embodiment illustrated in Figure 6 A provides a larger surface area for the grounding ofthe antenna element 28.
[0110] Figure 6B illustrates another embodiment of an antenna element with improved grounding characteristics. In this embodiment, an antenna element 38 has a top portion 40, a middle portion 42 and a bottom portion 44. The antenna element 38 is provided with a plurality of grounding points 46 extending downward from the bottom portion 44 for improved grounding ofthe antenna element 38. In the embodiment illustrated in Figure 6B, four grounding points 46 are provided. The four grounding points 46 are positioned in an equally spaced apart configuration on one side ofthe bottom portion 44.
[0111] Figure 6C illustrates yet another embodiment of an antenna element with improved grounding characteristics. In this embodiment, an antenna element 48 has a top portion 50, a middle portion 52 and a bottom portion 54. The antenna element 48 is provided with a pair of grounding points 56 extending downward from the bottom portion 44. The two grounding points 46 are positioned at one end and the middle ofthe bottom portion 44 for improved grounding ofthe antenna element 48.
[0112] Figure 7A illustrates a side-view of a CLMD antenna element adapted to provide improved performance while maintaining a relatively small package size or footprint. The illustrated antenna element 58 includes a top portion 60, a middle portion 62 and a bottom portion 64. While the top portion 60 and the middle portion 62 are similar to those illustrated in the above-described embodiments, the embodiment illustrated in Figure 7A includes a bottom portion 64 having a N-shaped ridge pattern. The ridged pattern ofthe bottom portion 64 effectively provides a greater surface area for the bottom portion 64 without increasing the footprint ofthe antenna element 58. hi certain embodiments, the bottom of one or more ridge may serve as a grounding point, other embodiments, as illustrated in Figure 7A, a separate grounding point may be provided. Thus, improved performance is achieved without increasing the size ofthe antenna element.
[0113] Figure 7B illustrates a variety of ridged patterns which may be applied to the bottom portion 64 ofthe antenna element 58 illustrated in Figure 7 A. As illustrated in Figure 7B, the size and shape ofthe ridges maybe varied to achieve desired performance characteristics of the antenna element.
[0114] Figure 7C illustrates another embodiment of an CLMD antenna element with improved performance without increasing or modifying the footprint. The antenna element 66 illustrated in Figure 7C includes a top portion 68 and a middle portion 70 similar to those described above. The antenna element 66 includes a bottom portion 72 having block ridges formed thereon. As illustrated in Figure 7D, the block ridges may be formed of a variety of shapes and sizes to provide the desired performance characteristics for the antenna element 66.
[0115] Figure 7E illustrates yet another embodiment of an CLMD antenna element with improved performance without improved footprint. The antenna element 74 illustrated in Figure 3E includes a top portion 76 and a middle portion 78 similar to those described above. The antenna element 74 includes a bottom portion 80 having saw-tooth ridges formed thereon. As illustrated in Figure 3F, the saw-tooth ridges may be formed of a variety of shapes and sizes to provide the desired performance characteristics for the antenna element 66. [0116] Figure 8A-8C illustrate an antenna element arrangement for providing a different field distribution and increased grounding ofthe antenna element. The antenna element arrangement 82 includes an antenna element 84 grounded on a grounding plane 86 by a pair of grounding points 88, 90. The antenna element 84 is positioned substantially perpendicular to the plane ofthe grounding plane 86. A metallic reflector 92, 94 is provided on each side of the antenna element 84. The reflectors 92, 94 are positioned substantially perpendicular to the plane ofthe grounding plane 86 and substantially perpendicular to the plane ofthe antenna element 84. Thus, the metallic reflectors 92, 94 serve to improve the radiation efficiency ofthe antenna element 84 by altering the field distribution.
[0117] Figure 9A illustrates an embodiment of an antenna element arrangement in accordance with the present invention. The antenna element arrangement 96 includes an antenna element 98 positioned atop a ground plane 100 and grounded through a ground pad 102. A coplanar wave guide (CPWG) 104 is provided on the board ofthe communication system to feed the antenna element 98. CPWG's are well known to those skilled in the art. The CPWG 104 provides the antenna element 98 with improved isolation characteristics. Figure 9B illustrates a radio frequency (RF) schematic corresponding to the embodiment illustrated in Figure 9 A. As noted above, the CPWG 104 is in communication with the antenna element 98.
[0118] Figure 9C illustrates another embodiment of an antenna element arrangement in accordance with the present invention. The arrangement 106 includes an antenna element 108 positioned atop a ground plane 110 and grounded through a ground pad 112. A CPWG 114 is provided in communication with the antenna element 108. Further, the arrangement 106 includes a single-stub resonator 116. The position, line, and width ofthe stub 116 on the line (CPWG) are dependent upon the input impedance ofthe antenna. Stubs are well known to those skilled in the art and can be either open-circuited or short-circuited. The arrangement 106 may include any number of stubs 116. The number of studs may be selected depending on the bandwidth requirements ofthe antenna element 108. Stubs are low-Q systems, collecting energy at the frequency near that ofthe antenna. This energy is then leaked from the stub and radiated by the antenna, thus improving the bandwidth ofthe antenna. Figure 9D illustrates an RF schematic ofthe embodiment illustrated in Figure 9C.
[0119] Figure 9E illustrates yet another embodiment of an antenna element arrangement in accordance with the present invention. The arrangement 118 includes an antenna element 120 positioned atop a ground plane 122 and grounded through a ground pad 124. A CPWG 126 is provided in communication with the antenna element 120. Further, the arrangement 118 includes two stubs 128a, 128b. The two stubs 128a, 128b create two different resonant frequencies, which may be used to improve the bandwidth ofthe antenna element 120. Again, the position, line, and width ofthe stub on the line (CPW) are dependent upon the input impedance ofthe antenna. Figures 9F-9H illustrate various embodiments of radio frequency (RF) schematics ofthe antenna element arrangement described above with reference to Figure 9E.
[0120] Figure 10A illustrates an antenna element similar to that described above with reference to Figures 5A and 5B. The antenna element 130 includes a top portion 132 and a middle portion 134 that are separated by a gap of size d. An electric field 136 is formed in the gap between the top portion 132 and the middle portion 134 when the antenna element is charged. The size ofthe gap, d, affects the confinement ofthe electric field 136 and, thus, the isolation and bandwidth ofthe antenna element 130. A smaller gap size, d, results in a more confined electric field, providing increased isolation and shielding for the antenna element 130. Conversely, a larger gap size, d, results in a less confined electric field 136, providing reduced isolation and shielding, but a larger bandwidth. [0121] Figures 10B and IOC are cross-sectional views along NLB-VIB of Figure 10A and illustrate the shape ofthe electric field 136 with variations is the size ofthe gap. Figure 10B illustrates an electric field for a relatively small gap size, while Figure IOC illustrates the electric field for a relatively large gap size.
[0122] Figure 10D illustrates an embodiment of an antenna element adapted to provide greater bandwidth without reducing shielding. The illustrated antenna element 138 includes a top portion 140, a middle portion 142 and a bottom portion 144. In this embodiment, the middle portion 142 is angled downward as it protrudes inward. This angled configuration results in a tapered gap 146 between the top portion 140 and the middle portion 142. The tapered gap 146 provides the antenna element 138 with greater bandwidth capability without sacrificing shielding.
[0123] Figures 11 A-l IC illustrate additional embodiments of antenna elements having variable gaps between the top portions and the middle portions. Figure 11 A illustrates an antenna element 148 having a top portion 150 and a middle portion 152. The middle portion 152 is provided with a downwardly stepped configuration to provide a gap 154 with a variable size between the top portion 150 and the middle portion 152. Although the embodiment illustrated in Figure 11 A is provided with a middle portion 152 having three steps, other embodiments may have any practical number of steps.
[0124] Figure 1 IB illustrates an antenna element 156 having a top portion 158 and a middle portion 160. The middle portion 160 is upwardly angled to provide a tapered gap 162 with a variable size between the top portion 158 and the middle portion 160.
[0125] Figure 1 IC illustrates an antenna element 166 having a top portion 168 and a middle portion 170. The middle portion 170 is provided with a upwardly stepped configuration to provide a gap 172 with a variable size between the top portion 168 and the middle portion 170.
[0126] Figures 12A-12D illustrate further embodiments of antenna elements in accordance with the present invention. The illustrated embodiments provide antenna elements with reduced sizes (or footprints) without a decrease in performance.
[0127] Figure 12A illustrates an antenna element 174 with a top portion 176, a middle portion 178 and a bottom portion 180. In this embodiment, a larger surface area for the middle portion 178 is achieved through a ridged configuration. In the illustrated embodiment, the middle portion 178 is provided with a plurality of block ridges to maintain the electric field strength between the top portion 176 and the middle portion 178 while reducing the footprint ofthe antenna element 174. Other embodiments may include slanted ridges 179 or rounded ridges 181, as illustrated in Figure 12 A.
[0128] Figure 12B illustrates an antenna element 182 with a top portion 184, a middle portion 186 and a bottom portion 188. In this embodiment, a larger surface area for the top portion 184 is achieved through a ridged configuration. In the illustrated embodiment, the top portion 184 is provided with a plurality of block ridges to maintain the electric field strength between the top portion 184 and the middle portion 186 while reducing the footprint ofthe antenna element 182.
[0129] Figure 12C illustrates an antenna element 190 with a top portion 192, a middle portion 194 and a bottom portion 196. h this embodiment, both the top portion 192 and the middle portion 194 are provided with a ridged configuration, resulting a larger surface area for each. As with the embodiments described above with reference to Figures 12A and 12B, the ridged configurations allow the antenna element 190 to maintain the electric field strength between the top portion 192 and the middle portion 194 while reducing the footprint ofthe antenna element 182. Configuring both the top portion 192 and the middle portion 194 with ridges allows for an increased reduction in the footprint.
[0130] Figure 12D illustrates an antenna element 198 with a top portion 200, a middle portion 202 and a bottom portion 204. In this embodiment, both the top portion 192 and the middle portion 194 are provided with parallel ridges. Thus, the top portion 200 and the middle portion 202 track each other, maintaining a constant gap size between them. As with the embodiments described above with reference to Figures 12A-12C, the ridged configurations allow the antenna element 198 to maintain the electric field strength between the top portion 200 and the middle portion 202 while reducing the footprint ofthe antenna element 198.
[0131] The features ofthe embodiments ofthe antenna elements described above with reference to Figures 12A-12D effectively change the inductance or the capacitance ofthe CLMD antenna element. It will be understood by those skilled in the art that the various features may be combined to change both the inductance and capacitance in order to achieve desired antenna element characteristics.
[0132] Figures 13A-13D illustrate further embodiments of antenna elements in accordance with the present invention. The illustrated embodiments provide improved isolation by at least partially shielding the bottom plate ofthe antenna elements from a grounding plane and modifying the inductance component ofthe antenna elements.
[0133] Figure 13A illustrates an antemia element 206 with a top portion 208, a middle portion 210 and a bottom portion 212. The antenna element 206 is positioned atop a ground plane 214 and is grounded through a ground pad 216. The bottom portion 212 ofthe antenna element 206 is contoured to accommodate a shield 218 between the ground plane 214 and a portion ofthe bottom portion 212. In the illustrated embodiment, the bottom portion 212 is provided with a raised left side, allowing the shield 218 to be positioned from approximately the middle ofthe bottom portion 212 and extended leftward. The positioning ofthe shield 218 improves the isolation ofthe antenna element 206, thereby improving performance.
[0134] Figure 13B illustrates an antenna element 220 with a top portion 222, a middle portion 224 and a bottom portion 226. The antenna element 220 is positioned atop a ground plane 228 and is grounded through a ground pad 230. The bottom portion 226 ofthe antenna element 220 is contoured to accommodate a shield 232 between the ground plane 228 and a portion ofthe bottom portion 226. In the illustrated embodiment, the bottom portion 226 is provided with a raised central region, allowing the shield 232 to be positioned between the central region ofthe bottom portion 226 and the ground plane 228.
[0135] Figure 13C illustrates an antenna element 234 with a top portion 236, a middle portion 238 and a bottom portion 240. The antenna element 234 is positioned atop a ground plane 242 and is grounded through an extended ground pad 246. The bottom portion 240 of the antenna element 234 is entirely raised above the ground plane 242. A shield 248 is positioned between the bottom portion 240 and the ground plane 242 to provide improved shielding ofthe antenna element 234. In the illustrated embodiment, the shield 248 extends substantially the entire length ofthe bottom portion 240, but does not extend beyond the bottom portion 240.
[0136] Figure 13D illustrates an antenna element 250 with a top portion 252, a middle portion 254 and a bottom portion 256. The antemia element 250 is positioned atop a ground plane 258 and is grounded through an extended ground pad 260. The bottom portion 256 of the antenna element 250 is entirely raised above the ground plane 258. A shield 262 is positioned between the bottom portion 256 and the ground plane 258 to provide improved shielding ofthe antenna element 250. In the illustrated embodiment, the shield 248 extends beyond one side ofthe bottom portion 240 to provide improved isolation ofthe antenna element 250.
[0137] Figure 14 illustrates another embodiment of an antenna element arrangement in accordance with the present invention, hi the illustrated arrangement 264, a planar CLMD antenna element 266 is positioned in the same plane as a ground plane 268. A line 270, such as a micro-strip line or a coplanar waveguide, for example, is provided to feed power to the antenna element 266. The antenna element 266 is grounded through a ground pad 272 to the ground plane 268. Thus, a very low profile, highly efficient and isolated antenna element arrangement is achieved.
[0138] Figure 15A illustrates another embodiment of an antenna element arrangement for achieving a very low profile and improved efficiency and isolation. In the illustrated arrangement 274, a planar CLMD antenna element 276 is positioned in the same plane as a ground plane 278. A line 280, such as a micro-strip line or a coplanar waveguide, for example, is provided to feed power to the antenna element 276. In this embodiment, the antenna element 276 is grounded to the ground plane 268 through a pair of ground pads 282 for improved grounding.
[0139] Figure 15B illustrates yet another embodiment of an antenna element arrangement for achieving a very low profile and improved efficiency and isolation. In the illustrated arrangement 284, a planar CLMD antenna element 286 is positioned in the same plane as a ground plane 288. The ground plane 288 is provided with a cutout 290 that is sufficiently large to accommodate the antenna element 286 therein. Thus, the antenna element 286 is surrounded on three sides by the ground plane. Positioning the antenna element 286 in this configuration provides improved isolation. The antenna element 286 is grounded to the ground plane 288 through a pair of ground pads 292. [0140] Figures 16A and 16B illustrate further embodiments of antenna element arrangements in accordance with the present invention. In these embodiments, multiple antenna elements may be provided in a single, low-profile arrangement.
[0141] Figure 16A illustrates an antenna element arrangement 294 having a ground plane 306. The ground plane 306 is provided with a plurality of cutouts 296, 298. In the illustrated embodiment, the ground plane 306 is provided with two cutouts 296, 298 positioned in two comers ofthe rectangular ground plane 306. In other embodiments, any number of cutouts may be provided, and the cutouts may be positioned at locations other than corners.
[0142] The arrangement 294 also includes a plurality of CLMD antenna elements 300, 302. The antenna elements 300, 302 are positioned in a coplanar manner with the ground plane 306 and within the cutouts 296, 298, respectively. This configuration improves the isolation ofthe antenna elements 300, 302 and results in a low-profile arrangement. Each antenna element 300, 302 is grounded to the ground plane 306 through ground pads 304 and is provided with power through feed lines 308. Thus, the illustrated arrangement 294 results in a low profile and improved isolation. Providing multiple antenna elements, such as antenna elements 300, 302 provides the arrangement with increased diversity.
[0143] hi the arrangement illustrated in Figure 16A, the antenna elements 300, 302 are positioned in a mirrored configuration with the bottom portion of each being faced toward the bottom portion ofthe other.
[0144] Figure 16B illustrates another embodiment of an antenna element arrangement for providing low profile, improved isolation and larger bandwidth. The illustrated arrangement 310 is provided with a ground plane 312 having a plurality of cutouts 314, 316. The arrangement 310 also includes a plurality of CLMD antenna elements 318, 320, positioned in a coplanar manner with the ground plane 312 and within the cutouts 314, 316, respectively. Each antenna element 318, 320 is grounded to the ground plane 312 through ground pads 322. In the arrangement illustrated in Figure 16B, the antenna elements 318, 320 are positioned in a mirrored configuration about a center axis ofthe ground plane 312 with a side of each facing a side ofthe other. In other embodiments, the antenna elements maybe positioned in various configurations, including positioning the antenna elements orthogonal to each other or at various angles.
[0145] Figure 17 illustrates another embodiment of an antenna element arrangement in accordance with the present invention. In the illustrated arrangement 324, a CLMD antenna element 326 is positioned in a coplanar manner with a ground plane 328 to provide a low profile. The antenna element 326 includes a top portion 330, a middle portion 332 and a bottom portion 334. A component 336 is positioned in the region between the middle portion 332 and the bottom portion 334. The component may be any component such as electrical components including passive and active components such as capacitors, resistors and chipsets. In other embodiments, the component may be positioned between the top plate 330 and the middle plate 332. In additional embodiments, more than one component may be positioned within the antenna element. In this manner, the footprint ofthe antenna element may be used to accommodate the components, thereby conserving valuable space in small devices.
46] Figures 18a-b illustrate respective three-dimensional and side views of one embodiments of a capacitively loaded magnetic dipole antenna 599. In one embodiment, antenna 599 comprises a first 501, a second 502, and a third 503 portion. In one embodiment, the first portion 501 is coupled to the third portion 503 by a first coupling portion 511, and the third portion 503 is coupled to second portion 502 by a second coupling portion 512. In one embodiment, antenna 599 comprises a feed area, generally indicated as feed area 509, where input or output signals are provided by a feed line 508 that is coupled to the third portion 503. In one embodiment, the first coupling portion 511 and the second coupling portion 512 are disposed relative to each other in a generally parallel relationship, hi one embodiment, first portion 501, second portion 502, and third portion 503 are disposed relative to each other in a generally parallel relationship. In one embodiment, first portion 501, second portion 502, and third portion 503 are disposed relative to each other in a generally coplanar relationship, h one embodiment, the portions 501, 502, and 503 are generally orthogonal to portions 511 and 512. In one embodiment, one or more of portions 501, 502, 503, 511, 512 are disposed in a generally orthogonal or parallel relationship relative to a grounding plane 506. It is understood, however, that the present invention is not limited to the described embodiments, as in other embodiments portions 501, 502, 503, 511, 512 may be disposed relative to each other and/or grounding plane 506 in other geometrical relationships and with other geometries. For example, first portion 501 may be coupled to third portion 503, and third portion 503 may be coupled to second portion 502 by respective coupling portions 511 and 512 such that one or more ofthe portions are disposed relative to each other in non-parallel, non-orthogonal, and/or non-coplanar relationships. In one embodiment, portions 501, 502, 503, 511, and 512 may comprise conductors. The conductors may be shaped to comprise one or more geometry, for example, cylindrical, planar, etc., or other geometries known to those skilled in the art. The conductors may be flexible, rigid, or a combination thereof.
[0147] In one embodiment, third portion 503 is disposed coplanarly with, or above, grounding plane 506. In one embodiment, third portion 503 is electrically isolated from grounding plane 506, other than where third portion 503 is coupled to grounding plane 506 at the grounding point 507. [0148] It is identified that third portion 503 may include one or more portion that is shaped to comprise other geometries, for example, a linear geometry, a curved geometry, a combination thereof, etc.
[0149] It is also identified that antenna 599 may be modeled as a radiative resonant LC circuit with a capacitance (C) that corresponds to a fringing capacitance that exists across a first void that is bounded generally by first portion 501 and second portion 502, and which is indicated generally as capacitive area 504; and with an inductance (L) that corresponds to an inductance that exists in a second void that is bounded generally by the second portion 502 and third portion 503, and which is indicated generally as inductive area 505.
[0150] It is further identified that the geometrical relationship between portions 501, 502, 503, 511, 512, and the gaps formed thereby, may be used to effectuate an operating frequency about which the antenna 599 resonates to radiate or receive a signal.
[0151] Figure 18C illustrates a three-dimensional view of an embodiment of a capacitively loaded magnetic dipole antenna 598. Some aspects of antenna 598 are similar to embodiments of antenna 599 described previously above and may be understood by those skilled in the art by referring to the description of antenna 599. However, it is identified that at least one aspect of antenna 598 differs from that of antenna 599. For example, in one embodiment, third portion 53 is defined by a length that is longer than a straight-line distance (c) between a first end (a) and a second end (b) of the third portion. In the illustrated embodiment, third portion 503 includes linear portions that are coupled in alternating orthogonal orientations. In one embodiment, the linear portions are disposed in generally parallel and/or orthogonal relationships relative to a grounding plane 506. It is identified that third portion 503 may include one or more portion that comprises or is coupled to comprise other geometries, for example, a linear geometry, a curved geometry, a combination thereof, etc. [0152] In one embodiment, portion 501, portion 502, and portion 503 are coupled to a substrate 515. In one embodiment substrate 515 comprises a high dissipation factor substrate, for example, a FR4 substrate known by those skilled in the art. In one embodiment, substrate 515 is defined by an outer periphery 516 and by an inner periphery 517, and the inner periphery defines a void within the substrate. In one embodiment, the capacitive area 504 generally spans the void.
[0153] It is identified that by coupling the first portion 501 and second portion 502 to a high dissipation factor substrate 515 such that the capacitive area 504 spans the void 517, the capacitance of antenna 598 maybe increased over that ofthe capacitance of antenna 599. As compared to a capacitance ofthe antenna 599, an antenna 598 that has an equivalent capacitance may be provided to comprise a smaller form-factor/profile, for example, as measured in a direction orthogonal to grounding plane 506.
[0154] It is also identified that by providing a third portion 503 that comprises a length that is longer than a straight line distance (c) between the first end (a) and the second end (b) of the third portion, the antenna 598 inductance in the inductive area 505 may be increased over that ofthe inductance ofthe antenna 599. As compared to an inductance of antenna 599, an antenna 598 that has an equivalent inductance may be provided to comprise a smaller form- factor/profile, for example, as measured in a direction orthogonal to grounding plane 506.
[0155] Figure 19 illustrates a three-dimensional view of a capacitively loaded magnetic dipole antenna 597. In one embodiment, antenna 597 comprises a first 501, a second 502, and a third 503 portion. It is identified that antenna 597 may be modeled as a radiative resonant LC circuit with a capacitance (C) that corresponds to a fringing capacitance that exists in a capacitive area 504 that is bounded generally by first portion 501 and second portion 502; and with an inductance (L) that corresponds to an inductance that exists in an inductive area 505 that is bounded generally by the second portion 502 and the third portion 503. In one embodiment, the first portion 501 is coupled to the third portion 503 by a first coupling portion 511, and the third portion 503 is coupled to a second portion 502 by a second coupling portion 512. In one embodiment, antenna 598 comprises a feed line 508 coupled to the third portion 503 where input or output signals are provided.
[0156] Some aspects of antenna 597 are similar to embodiments of antenna 599 described previously above and may be understood by those skilled in the art by referring to the description of antenna 599. However, it is identified that at least one aspect of antenna 597 differs from that of antenna 599. For example, in one embodiment, third portion 503 is defined by a length that is longer than a straight-line distance (c) between a first end (a) and a second end (b) ofthe third portion. Figure 19a also illustrates an embodiment of antenna 598 wherein third portion 503 is disposed in a generally non-coplanar relationship relative to the generally coplanar relationship ofthe first portion 501 and second portion 502. In one embodiment, third portion 503 may be disposed in a plane that his generally coplanar with, or above, a grounding plane 506. In one embodiment, third portion 503 may be electrically isolated from the grounding plane 506 other than where third portion 503 is coupled to grounding plane 506 at grounding point 507. It is identified that third portion 503 may include one or more portion that comprises or is coupled to comprise other geometries, for example, a linear geometry, a curved geometry, a combination thereof, etc.
[0157] hi one embodiment, the grounding plane 506 and/or one or more portion of third portion 503 may be disposed in a plane that is generally orthogonal to a coplanar relationship ofthe first portion 501 and the second portion 502. h one embodiment (not illustrated), the grounding plane 506 and/or one or more portion of third portion 503 may be disposed in a plane that is in a generally angular relationship relative to a substrate 515, which first portion 501 and second portion 502 are coupled to. In one embodiment, the angular relationship of third portion relative to substrate 515 may be between 0 and 180 degrees. In one embodiment, substrate 515 comprises a high dissipation factor substrate, for example, a FR4 substrate. In one embodiment, substrate 515 is defined by an outer periphery 516 and by an inner periphery 517, and the inner periphery defines a void within the substrate. In one embodiment, the capacitive area 504 spans the void.
[0158] It is identified that by coupling the first portion 501 and second portion 502 to a high dissipation factor substrate 515 such that the capacitive area 504 spans the void, the capacitance of antenna 597 may be increased over that ofthe capacitance of antenna 599. As compared to a capacitance of antenna 599, an antenna 597 that has an equivalent capacitance may be provided to comprise a smaller form-factor/profile.
[0159] It is also identified that by providing a third portion 503 that comprises a length that is longer than a straight line distance (c) between the first end (a) and the second end (b) of the third portion, the antenna 597 inductance in the inductive area 505 may be increased over that ofthe inductance of antenna 599. As compared to a capacitance of antenna 599, an antenna 597 that has an equivalent capacitance may be provided to comprise a smaller form- factor/profile.
[0160] It is also identified that by providing a third portion 503 that comprises a length that is longer than a straight line distance (c) between the first end (a) and the second end (b) of the third portion, the antenna 597 inductance in the inductive area 505 may be increased over that ofthe inductance of antenna 599. As compared to an inductance antenna 599, an antenna 597 that has an equivalent inductance may be provided to comprise a smaller form- factor/profile.
[0161] Figures 20a-b illustrate three-dimensional views of embodiments of an capacitively loaded magnetic dipole antenna 596 and 595. In one embodiment, the first portion 501 is coupled to the third portion 503 by a first coupling portion 511, and the third portion 503 is coupled to second portion 502 by a second coupling portion 512. In one embodiment, antenna 596 comprises a feline 508 coupled to the third portion 503 where input or output signals are provided
[0162] Some aspects of antenna 596 and 595 are similar to embodiments of antenna 599 described previously above and may be understood by those skilled in the art by referring to the description of antenna 599. However, it is identified that at least one aspect of antenna 596 and 595 differs from that of antenna 599. For example, in one embodiment, third portion 503 is defined by a length that is longer than a straight-line distance (c) between a first end (a) and a second end (b) ofthe third portion. Figures 20a and 20b also illustrate embodiments wherein at least one portion ofthe third portion 503 is disposed in a generally coplanar relationship relative to the generally coplanar relationship ofthe first portion 501 and second portion 592. It is identified that third portion 503 may include one or more portion that comprises or is coupled to comprise other geometries, for example, a linear geometry, a curved geometry, a combination thereof, etc.
[0163] Figures 20a-b also illustrate embodiments wherein at least one portion of third portion 503 may be disposed in a plane that is generally coplanar with, or above, a grounding plane 506. In one embodiment, third portion 593 is electrically isolated from the grounding plane 506 other than where third portion 503 is coupled to grounding plane 506 at a grounding point 507.
[0164] In one embodiment (not illustrated), the grounding plane 506 and/or at least a portion of third portion 503 may be disposed in a plane that is in an angular relationship relative to a coplanar relationship of first portion 501 and second portion 502. In one embodiment, the angular relationship relative to substrate 515 and may be between 0 and 180 degrees. [0165] In one embodiment substrate 515 comprises a high dissipation factor substrate, for example, a FR4 substrate. In one embodiment, substrate 515 is defined by an outer periphery 516 and by an inner periphery 517, and the inner periphery defines a void within the substrate. In one embodiment, the capacitive area 504 generally spans the void.
[0166] It is identified that by coupling the first portion 501 and second portion 502 to a high dissipation factor substrate 515 such that the capacitive area spans the void 517, the capacitance of antennas 596 and 595 may be increased over that ofthe capacitance of antenna 599. As compared to a capacitance of antenna 599, an antenna 596 and 595 that has an equivalent capacitance may be provided to comprise a lower form-factor/profile.
[0167] It is also identified that by providing a third portion 503 that comprises a length that is longer than a straight line distance (c) between the first end (a) and the second end (b) of the third portion, the inductance of antenna 596 and 595 that has an equivalent inductance may be provided to comprise a lower form-factor/profile.
[0168] Figure 23 illusfrates a single-mode capacitively loaded antenna. If we assume that the structure in Figure 23 can be modeled as a Li circuit, then Ci is the capacitance across gap g. Inductance Li is mainly contributed by the loop designated by the numeral 702. The gap g is much smaller than the overall thickness ofthe antenna. The presence of only one LC circuit limits this antenna design to operating at a single frequency.
[0169] Figure 24 illustrates a dual-mode antenna based on the same principles as the antenna shown in Figure 23. Here, a second antenna element is placed inside the first antenna element described above. This allows tuning one to a certain frequency ft and the other one to another frequency f2. The two antennas have a common ground, but different capacitive and inductive elements. [0170] Figure 25 illusfrates a multimode antenna with shared inductances L] and L2. and discrete capacitances , C2, and C . The antenna comprises several antenna elements.
[0171] One embodiment ofthe present invention relates to an antenna with the radiating elements and the conductor lying in substantially the same plane. The radiating elements and the planar element have a thickness that is much less then either their length or width; thus they are essentially two dimensional in nature. Preferably the antenna structure is affixed to a substrate. Figure 26 illustrates an antenna 10 in accordance with the principles ofthe present invention that is formed flat on a subsfrate 712. The antenna is substantially two-dimensional in nature. The antenna comprises a planar conductor 714, a first parallel elongated conductor 716, and a second parallel elongated conductor 718. The planar conductor is positioned in the same plane as the electric field, known as the E-plane. The E-plane of a linearly polarized antenna contains the electric field vector ofthe antenna and the direction of maximum radiation. The E-plane is orthogonal to the H-plane, i.e. the plane containing the magnetic field. For a linearly polarized antenna, the H-plane contains the magnetic field vector and the direction of maximum radiation. Each of elongated conductors 716 and 718 are electrically connected to the planar conductor 714 by respective connecting conductors 720 and 722. Antenna 710 comprises elongated conductors 716 and 718 that are in the same or substantially the same plane as the planar conductor 714. The gap between the elongated conductor 716 and the elongated conductor 718 is the region of capacitance. The gap between the elongated conductor 716 and the planar conductor 714 is the region of inductance. In a preferred embodiment, the space between the first elongated conductor 716 and the second elongated conductor 718 is much less than the space between the first elongated conductor 716 and the planar conductor 714.
[0172] In an alternative embodiment, shown in Figure 26, the radiating element and the conductor may be isolated, hi Figure 27, a grounded planar conductor 732 is isolated from a radiating element 730 by an etched area 734. An antenna feed 736 is supplied and a return for the ground 738 is supplied. The antenna feeds 736, or feed lines, are fransmission lines of assorted types that are used to route RF power from a transmitter to an antenna, or from an antenna to a receiver. In accordance with the principles ofthe present invention any ofthe antenna structures discussed herein could utilize an etched area or other means to isolate the radiating element or elements.
[0173] Another embodiment ofthe present invention relates to the use ofthe antenna structure previously described having an essentially two-dimensional structure, in combination with another planar conductor. The second planar conductor may be located on a opposite face ofthe substrate. Preferably, the two planar conductors are substantially parallel to each other. Figures 28A-28C show an antenna 740 with planar conductors 744 and 746 on opposite sides ofthe substrate 742. Vias 750 and 752 provide the antenna feed and shorts to ground, respectively. The vias 750 and 752 connect the radiating elements to the planar conductor 746.
[0174] In another embodiment, the antenna structure may utilize more than one radiating element. The radiating elements may be arranged side-by-side as showing in Figures 29A- 29C. Figures 29A-29C show a dual frequency antenna structure, similar to the single element structure of Figures 28A-28C The antenna structure has radiating elements 760 and 762 arranged side-by-side. Each radiating element has vias connecting the radiating element to the planar conductor on the opposite face ofthe substrate. The planar conductors are substantially parallel to each other.
[0175] Alternatively, the radiating structures may be placed in a nested configuration as shown in Figure 30. Figure 30 shows another dual frequency arrangement implementing the design of Figure 24 on a substrate in a manner similar to Figure 26. In yet another embodiment ofthe present invention, the antenna structure may utilize three or more radiating elements. The radiating elements may all be located on the same face as the planar conductor. Figure 31 shows an antenna structure similar to that of Figure 30, but with an additional conductor 770 to increase the frequency diversity.
[0176] Figures 32A-32B show an antenna structure on a substrate 780. Face A of subsfrate 780 carries a three frequency antenna structure as shown in Figure 731. Face B of substrate 780 carries a single frequency antenna structure as shown in Figure 25, although alternatively this could also be a multifrequency structure or any combination of single and multifrequency structures.
[0177] In an another embodiment, the antenna structure may comprise conductors on any of the faces ofthe substrate. The conductors may be located in parallel and opposite arrangements or asymmetrically. Figures 33A-33B show an antenna structure 790 with conductors formed, such as by conventional printed circuit methods, on the edges as well as the face surface ofthe substrate 792. This allows even more space savings in certain packaging configurations.
[0178] In yet another embodiment, more than one substrate may be used. As shown in Figures 34A-34B, an second substrate bearing additional conductors can be utilized. The second substrate may be located perpendicular to the first subsfrate. As shown in Figures 34A-34B, a primary substrate 800 carries a multifrequency antemia structure, such as the one shown in Fig. 31. A secondary substrate 802 is mounted substantially perpendicular to the primary substrate. The substrate 802 carries a single frequency antenna structure, although alternatively this too could be a multifrequency structure.
[0179] In addition, in accordance with the principles ofthe present invention more than one secondary substrate may be utilized. Figures 35A-35B show additional arrangements, similar to Figures 34A-34B, wherein a plurality of secondary substrates, each carrying respective antenna structures, are mounted on a primary substrate.
[0180] Furthermore, the secondary subsfrate may be arranged in any configuration, not only in perpendicular positions. Figure 36 illustrates an antenna 810 on a substrate 812 that is extended relative to substrate 814. This allows installation ofthe antenna in an enclosure with a shape that just allows an antenna along the side ofthe enclosure.
[0181] Figure 37 illustrates a configuration similar to that of Figure 36, but with two antennas for frequency diversity.
[0182] An antenna structure in accordance with the principles of the present invention may be integrated into an electronic device. The previously discussed benefits ofthe present invention make such an antenna structure well suited to use in small electronic devices, for example, but not limited to mobile telephones. Figure 38 shows the antenna structure of Figure 37 housed within an enclosure, such as the case of a mobile telephone or other electronic device.
[0183] Figure 39 illustrates a configuration similar to that of Figure 37, but with four radiating elements, including elements carried on secondary substrates 820 and 822.
[0184] Figure 40 shows the antenna structure of Figure 39 housed within an enclosure, such as the case of a mobile telephone or other electronic device. The low profile ofthe antenna ofthe present invention allows for the antenna to be placed easily within electronic devices without requiring «a specifically dedicated volume.
[0185] Figure 41 illustrates a circuit board 130 with radiating elements 832 and 834 disposed at opposite ends thereof. Similarly, in Figure 42, an electronic device, such as a laptop computer 840, is configured with a plurality of radiating elements. Owing to their construction, the radiating elements may be arranged within the computer wherever space is available. Thus, the design ofthe computer housing need not be dictated by the antenna requirements.
[0186] In yet another alternative embodiment, the antenna structure may comprise grooves. The grooves may be partially or completely through the substrate in various locations, such as between the radiating elements. Figure 43 illustrates an antenna ofthe type generally shown in Figure 27. The antenna is formed, such as by conventional printed circuit techniques, on a substrate 850. A groove 852 is milled partially or completely through the substrate in the capacitive region ofthe antenna to improve the efficiency ofthe antenna.
[0187] Figure 44 illusfrates the same concept shown in Figure 43, but in the case of a multifrequency antenna. Here, a plurality of grooves 862 are milled into substrate 860 between each pair of radiating conductors.
[0188] The antenna structures in accordance with the principles of the present invention may be made by any means known in the art such as the use of traditional circuit printing. Figure 45 illustrates an alternative method for fabricating an antenna in accordance with the present invention. Rather than etching the antenna pattern on a printed circuit board, here the antenna is etched on a metallic film that is then molded in plastic. The resulting structure may be attached in various ways to a circuit board or to a device enclosure.
[0189] Accordingly, while embodiments and implementations ofthe invention have been shown and described, it should be apparent that many more embodiments and implementations are within the scope ofthe invention. Therefore, the invention is not to be restricted, except in light ofthe claims and their equivalents.
[0190] Wireless communication systems and devices operating in one or more frequency bands and utilizing one or more embodiments described herein are considered to be within the scope ofthe invention, for example, systems and devices such as PDAs, cell phones, etc. [0191] While particular embodiments ofthe present invention have been disclosed, it is to be understood that various different modifications and combinations are possible and are contemplated within the true spirit and scope ofthe appended claims. There is no intention, therefore, of limitations to the exact abstract or disclosure herein presented.
[0192] Thus, it will be recognized that the preceding description embodies one or more invention that may be practiced in other specific forms without departing from the spirit and essential characteristics ofthe disclosure and that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims.

Claims

WHAT IS CLAIMED IS:
1. An antenna element, comprising:
a top portion; a bottom portion positioned parallel to the top portion; a middle portion positioned parallel to the top portion and the bottom portion and positioned between the top portion and the bottom portion; and at least one ground pad adapted to ground the antenna element to a ground plane, the ground pads being further adapted to contact the ground plane at more than a single point.
2. The antenna element of claim 1, wherein the ground pad is elongated and extends along at least a portion ofthe bottom portion.
3. The antenna element of claim 1 , wherein the at least one ground pad includes a plurality of ground pads distributed along at least a portion ofthe bottom portion.
4. An antenna element, comprising:
a top portion; a bottom portion positioned parallel to the top portion; and a middle portion positioned parallel to the top portion and the bottom portion and positioned between the top portion and the bottom portion; wherein at least one ofthe top, bottom and middle portions is provided with ridges.
5. The antenna element of claim 4, wherein the ridges are V-shaped.
6. The antenna element of claim 4, wherein the ridges are block shaped.
7. The antenna element of claim 4, wherein the ridges are saw-tooth shaped.
8. The antenna element of claim 4, wherein the ridges on two or more of the top portion, the bottom portion and the middle portion track each other.
9. An antenna element arrangement, comprising:
an antenna element positioned atop a ground plane and being grounded to the ground plane; and at least two deflectors positioned around the antenna element, the deflectors being adapted to deflect an electric field generated by the antenna element.
10. The antenna element of claim 9, wherein the antenna element is positioned substantially perpendicular to the ground plane.
11. The antenna element of claim 10, wherein the deflectors are positioned perpendicular to the ground plane and to the antenna element.
12. The antenna element of claim 9, wherein the deflectors are metallic.
13. An antenna element arrangement, comprising:
an antenna element positioned atop a ground plane and being grounded to the ground plane; and a wave guide in communication with the antenna element and being adapted to direct an electric field generated by the antenna element.
14. The antenna element of claim 13, further including at least one stub resonator adapted to collect RF energy and to direct the energy to the antenna element.
15. An antenna element, comprising:
a top portion; a bottom portion positioned parallel to the top portion; and a middle portion positioned parallel to the top portion and the bottom portion and positioned between the top portion and the bottom portion, thereby forming a gap between the top portion and the middle portion; wherein the gap varies in size along a length ofthe middle portion.
16. The antenna element of claim 15, wherein the middle portion is angled relative to the top portion to produce a varying gap size.
17. The antenna element of claim 15, wherein the middle portion is stepped to produce a varying gap size.
18. An antenna element arrangement, comprising:
an antenna element positioned atop a ground plane and being grounded to the ground plane, the antenna element having a bottom portion; and a shield positioned between the ground plane and at least a portion ofthe bottom portion of the antenna element.
19. The antenna element arrangement of claim 18, wherein the lower portion substantially resting on the ground plane and a raised portion, and wherein the shield is positioned between the raised portion and the ground plane.
20. The antenna element arrangement of claim 19, wherein the raised portion is on one end ofthe bottom portion ofthe antenna element.
21. The antenna element arrangement of claim 19, wherein the raised portion is in a central region ofthe bottom portion ofthe antenna element.
22. The antenna element arrangement of claim 18, wherein the shield is positioned between substantially a length ofthe bottom portion and the ground plane.
23. The antenna element arrangement of claim 22, wherein the shield extends beyond the length ofthe bottom portion and the ground plane.
24. An antenna element arrangement, comprising:
a ground plane; and at least one antenna element positioned in a coplanar configuration with the ground plane and being grounded to the ground plane.
25. The antenna element arrangement of claim 24, wherein the ground plane is provided with at least one cutout to accommodate the antenna element therein.
26. The antenna element arrangement of claim 25, wherein the ground plane is provided with two or more cutouts, each cutout having an antenna element therein.
27. The antenna element arrangement of claim 26, wherein the antenna elements in the cutouts are positioned in a mirrored configuration relative to each other.
28. The antenna element arrangement of claim 26, wherein the antenna elements in the cutouts are positioned in an orthogonal configuration relative to each other.
29. An antenna element arrangement, comprising:
a ground plane; an antenna element being grounded to the ground plane, the antenna element having a top portion, a bottom portion being substantially parallel to the top portion, and a middle portion being substantially parallel to the top portion and the bottom portion and being positioned therebetween; and at least one component positioned in a gap between two ofthe top portion, the bottom portion and the middle portion.
30. The antenna element arrangement of claim 29, wherein the component is an electrical component.
31. An antenna comprising:
a first planar conductor; a first elongated conductor and a second elongated conductor, which are each substantially coplanar with the planar conductor; the first elongated conductor having a first end electrically connected to the planar conductor and a second end; and the second elongated conductor, parallel to the first elongated conductor and spaced apart therefrom, having a first end electrically connected to the planar conductor.
32. The antenna of claim 1, wherein the first end ofthe first elongated conductor is electrically connected to the first planar conductor by a first connecting conductor and the first end ofthe second elongated conductor is electrically connected to the first planar conductor by a second connecting conductor.
33. The antenna of claim 1, wherein the first connecting conductor and the second connecting conductor are perpendicular to the first elongated conductor and second elongated conductor respectively.
34. The antenna of claim 1 further compromising a third elongated conductor spaced apart from the planar conductor and electrically connected to at least one ofthe first end ofthe first elongated conductor and the first end ofthe second elongated conductor.
35. The antenna of claim 4, wherein the first end ofthe first elongated conductor is electrically connected to the third elongated conductor by a first connecting conductor perpendicular to the first elongated conductor and the first end ofthe second elongated conductor is electrically connected to the third elongated conductor by a second connecting conductor perpendicular to the second elongated conductor.
36. The antenna of claim 4, wherein the third elongated conductor is electrically connected to the planar conductor.
37. The antenna of claim 1 further comprising a substrate and wherein the planar conductor, the first elongated conductor, and the second elongated conductor are disposed on a first side ofthe substrate.
38. The antenna of claim 1 further comprising a substrate and wherein the planar conductor is disposed on a first side ofthe substrate and the first elongated conductor and the second elongated conductor are disposed on a second side ofthe substrate.
39. The antenna of claim 8 further comprising a second planar conductor disposed on the second side ofthe substrate.
40. The antenna of claim 9, wherein the first end ofthe first elongated conductor and the first end ofthe second elongated conductor are electrically connected to the first planar conductor by vias through the substrate.
41. The antenna of claim 1 , wherein the first elongated conductor and the second elongated conductor comprise a first element and further wherein the antenna comprises a second element.
42. The antenna of claim 11 , wherein the first element and the second element are disposed in a side-by-side relationship.
43. The antenna of claim 11 , wherein the second element is disposed between the first element and the planar conductor.
44. The antenna of claim 11, wherein at least one ofthe first and second elements further comprises a third elongated conductor having a first end electrically connected to the planar conductor.
45. The antenna of claim 11 further comprising a substrate and wherein the first element and the second element are disposed adjacent to opposing edges ofthe substrate.
46. The antenna of claim 11 further comprising a primary substrate with the first element disposed thereon and a secondary substrate attached to the primary substrate with the second element disposed thereon.
47. The antenna of claim 16 further comprising a plurality of secondary substrates attached to the primary substrate with a corresponding plurality of second elements disposed thereon.
48. The antenna of claim 17, wherein each ofthe plurality of secondary substrates is perpendicular to the primary substrate.
49. The antenna of claim 1 further comprising a substrate and at least one conductor along an edge ofthe substrate.
50. The antenna of claim 1 further comprising:
a primary subsfrate; a secondary substrate attached to the primary subsfrate and perpendicular thereto; and a third parallel elongated conductor and a fourth parallel elongated conductor on the secondary substrate, each having a first end electrically connected to the planar conductor.
51. The antenna of claim 20 comprising a plurality of secondary substrates attached to the primary substrate and perpendicular thereto, each ofthe secondary substrates having respectively a third parallel elongated conductor and a fourth parallel elongated conductor thereon.
52. The antenna of claim 1, wherein the first planar conductor, the first elongated conductor, and the second elongated conductors are disposed on a first side of a substrate and further comprising a second planar conductor and a third parallel elongated conductor and a fourth parallel elongated conductor each having a first end electrically connected to the second planar conductor and disposed on a second side ofthe substrate.
53. An antenna comprising:
a substrate; a first planar conductor disposed on a first side ofthe substrate; a second planar conductor disposed on a second side ofthe substrate; a first elongated conductor disposed on the substrate; the first elongated conductor having a first end electrically connected to one ofthe first planar conductor and the second planar conductor; a second elongated conductor disposed on the substrate and having a first end electrically connected to one ofthe first planar conductor and the second planar conductor.
54. The antenna of claim 23, wherein the first elongated conductor and the second elongated conductor are disposed on the first side ofthe substrate.
55. The antenna of claim 24, wherein the first end ofthe first elongated conductor and the first end ofthe second elongated conductor are electrically connected to the second planar conductor.
56. The antenna of claim 23, wherein the first elongated conductor and the second elongated conductor comprise a first element and further wherein the antenna comprises a second element.
57. The antenna of claim 26, wherein the first element and the second element are disposed in a side-by-side relationship.
58. The antenna of claim 26, wherein at least one ofthe first element and second element further comprises a third elongated conductor having a first end electrically connected to one ofthe first planar conductor and the second planar conductor.
59. The antenna of claim 24, wherein the first end ofthe first elongated conductor and the first end ofthe second elongated conductor are electrically connected to the first planar conductor.
60. The antenna of claim 29 further comprising a third elongated conductor and a fourth elongated conductor disposed on the second side ofthe substrate, each having a first end electrically connected to the second planar conductor.
61. An antenna comprising:
a primary substrate; an at least one planar conductor disposed on the primary substrate; a first antenna element having a first parallel elongated conductor and a second parallel elongated conductor disposed on the primary substrate; the first parallel elongated conductor and the second parallel elongated conductor each having a first end electrically connected to the planar conductor.
62. The antenna of claim 31 further comprising:
a secondary subsfrate attached to the primary substrate and perpendicular thereto; a second antenna element having a third parallel elongated conductor and a fourth parallel elongated conductor disposed on the secondary substrate.
63. The antenna of claim 32 further comprising a plurality of secondary substrates attached to the primary substrate and perpendicular thereto, each having a corresponding second antenna element.
64. The antenna of claim 33, wherein at least some of the plurality of secondary substrates are disposed on a first side ofthe primary substrate and a remainder ofthe plurality of secondary substrates are disposed on a second side ofthe primary substrate.
65. An antenna comprising:
a substrate; a planar conductor disposed on the substrate; a first parallel elongated conductor and a second parallel elongated conductor disposed on the substrate, each having a first end electrically connected to the planar conductor, the first parallel elongated conductor, the second parallel elongated conductor, and the planar conductor located substantially in the E-plane.
66. The antenna of claim 35, wherein the substrate includes a groove at least partially therethrough between the first and second elongated conductors.
67. The antenna of claim 35 further comprising at least a third elongated conductor parallel to the first elongated conductor and the second elongated conductor, the third conductor having a first end electrically connected to the planar conductor and wherein the substrate includes at least two grooves at least partially therethrough between pairs ofthe first, second and third elongated conductors.
68. A wireless device comprising:
a first portion; a second portion, the first and second portion disposed to effectuate a capacitive area; and a third portion, the third portion coupled to the first portion and to the second portion to effectuate an inductive area, wherein the third portion comprises a length having a first end and a second end, wherein the length is longer than a straight line distance between the first end and the second end, and wherein the first portion, the second portion, and the third portion define a capacitively coupled dipole antenna.
69. A dipole antenna comprising:
a first portion; a second portion, the first and second portion disposed to create a capacitive area; and a third portion, the third portion comprising one or more portion, the third portion coupled to the first portion and to the second portion to crate an inductive area, wherein the third portion comprises a length having a fist end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end.
70. The antenna of claim 2, wherein one or more portion ofthe third portion is disposed relative to the first portion and the second portion in a non-parallel relationship.
71. The antenna of claim 2, wherein one or more portion of the third portion is disposed relative to the first portion and the second portion in a parallel relationship.
72. The antenna of claim 2, wherein the first and second portion are disposed in a generally coplanar relationship, and wherein one or more portion ofthe third portion is disposed in a plane that is in angular relationship relative to the coplanar relationship ofthe first and second portion.
73. The antenna of claim 2, wherein the first portion, the second portion, and the third portion are disposed on or above a ground plane.
74. The antenna of claim 6, wherein the antenna comprises a substrate, wherein the fist portion and the second portion are coupled to the substrate, and wherein the ground plane is disposed in an angular relationship relative to the substrate.
75. The antemia of claim 2, wherein the antenna comprises a high dissipation factor subsfrate, and wherein the first and second portion are coupled to the high dissipation factor substrate.
76. The antenna of claim 2, wherein the antenna comprises a FR4 substrate.
77. The antenna of claim 9, wherein the FR4 substrate is defined by a periphery, wherein within the periphery the FR4 substrate defines a void, wherein the capacitive area generally spans the void.
78. The antenna of claim 2, wherein the first portion, the second portion, and the third portion are coupled to create a capacitively coupled dipole antenna.
79. A system comprising:
a dipole antenna including, a first portion; a second portion, the first and second portion disposed in a relationship to create a capacitive area; and a third portion, the third portion coupled to the first portion and to the second portion and disposed to create an inductive area, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the fist end and the second end.
80. The system of claim 12, wherein the antenna further includes a high dissipation factor substrate.
81. The system of claim 12, wherein the antenna comprises an FR4 substrate.
82. The system of claim 12, wherein the system comprises a wireless communications device.
83. The system of claim 14, wherein the first and second portion are coupled to the FR4 substrate, wherein the FR4 substrate is defined by a periphery, wherein within the periphery the FR4 substrate defines a void, and wherein the capacitive area generally spans the void.
84. The system of claim 12, wherein the system comprises a wireless communications device.
85. A capacitively coupled dipole antenna, comprising:
capacitance means for creating a capacitance; and inductive means for creating an inductance.
86. The antemia of claim 17, further comprising a first portion, a second portion, and a third portion, wherein the third portion comprises a length having a first end and a second end, and wherein the length is longer than a straight line distance between the first end and the second end.
87. The antenna of claim 18, wherein the antenna further comprises a substrate.
88. The system of claim 19, wherein the first and second portion are coupled to the substrate, wherein the substrate is defined by a periphery, wherein within the periphery the substrate defines a void, and wherein the capacitance generally spans the void.
89. A method for creating resonance in a resonant circuit, comprising the steps of:
providing a first portion; providing a second portion; disposing the first and second portion to create a capacitive area; and providing a third portion, wherein the third portion comprises a length having a first end and a second end, and wherein within the periphery the high dissipation factor substrate defines a void, and wherein the capacitive area generally spans the void.
90. The method of claim 21, further comprising the step of:
providing a high dissipation factor substrate, wherein the high dissipation factor substrate is defined by a periphery, wherein within the periphery the high dissipation factor substrate defines a void, and wherein the capacitive area generally spans the void.
PCT/US2003/040663 2002-12-17 2003-12-17 Antennas with reduced space and improved performance WO2004057698A2 (en)

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AU2003303179A AU2003303179A1 (en) 2002-12-17 2003-12-17 Antennas with reduced space and improved performance
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US10/322,196 2002-12-17
US10/322,196 US7084813B2 (en) 2002-12-17 2002-12-17 Antennas with reduced space and improved performance
US10/375,423 US8059047B2 (en) 2003-02-27 2003-02-27 Capacitively loaded dipole antenna optimized for size
US10/375,423 2003-02-27
US10/643,102 2003-08-18
US10/643,102 US7616164B2 (en) 2003-02-27 2003-08-18 Optimized capacitive dipole antenna

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AU2003303179A1 (en) 2004-07-14
WO2004057698A3 (en) 2006-06-29
WO2004057698A2 (en) 2004-07-08
EP1579529A2 (en) 2005-09-28
AU2003303179A8 (en) 2004-07-14
EP1579529A4 (en) 2007-09-19

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