US20240030610A2 - Monopole wire-patch antenna with enlarged bandwidth - Google Patents

Monopole wire-patch antenna with enlarged bandwidth Download PDF

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Publication number
US20240030610A2
US20240030610A2 US18/086,812 US202218086812A US2024030610A2 US 20240030610 A2 US20240030610 A2 US 20240030610A2 US 202218086812 A US202218086812 A US 202218086812A US 2024030610 A2 US2024030610 A2 US 2024030610A2
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Prior art keywords
wire
patch antenna
impedance
antenna according
capacitive
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US18/086,812
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US20230208038A1 (en
Inventor
Kaoutar ALLABOUCHE
Serge BORIES
Christophe DELAVAUD
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Assigned to COMMISSARIAT A L'ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES reassignment COMMISSARIAT A L'ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BORIES, SERGE, DELAVEAUD, CHRISTOPHE, ALLABOUCHE, Kaoutar
Publication of US20240030610A2 publication Critical patent/US20240030610A2/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04—Resonant antennas
    • H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
    • H01Q9/045—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with particular feeding means
    • H01Q9/0457—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with particular feeding means electromagnetically coupled to the feed line
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/27—Adaptation for use in or on movable bodies
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/48—Earthing means; Earth screens; Counterpoises
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/30—Arrangements for providing operation on different wavebands
    • H01Q5/307—Individual or coupled radiating elements, each element being fed in an unspecified way
    • H01Q5/342—Individual or coupled radiating elements, each element being fed in an unspecified way for different propagation modes
    • H01Q5/357—Individual or coupled radiating elements, each element being fed in an unspecified way for different propagation modes using a single feed point
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/50—Feeding or matching arrangements for broad-band or multi-band operation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04—Resonant antennas
    • H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
    • H01Q9/0421—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with a shorting wall or a shorting pin at one end of the element
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04—Resonant antennas
    • H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
    • H01Q9/045—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with particular feeding means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04—Resonant antennas
    • H01Q9/30—Resonant antennas with feed to end of elongated active element, e.g. unipole
    • H01Q9/32—Vertical arrangement of element
    • H01Q9/36—Vertical arrangement of element with top loading

Definitions

  • the present invention relates to the field of antennas and more particularly to miniature antennas able to be integrated into embedded systems. More specifically, the invention relates to monopole wire-patch antennas.
  • the invention is applicable, by way of non-limiting example, to radiocommunication systems or to systems for fixing the geoposition of moving objects.
  • miniature antenna By “miniature antenna”, what is meant is an antenna having dimensions of the order of the wavelength of the minimum resonant frequency of operation, divided by 2 ⁇ . Miniature antennas have the advantage of being compatible with embedded systems and integrated circuits widely used in the fields of mobile devices, telephony, and geopositioning. However, miniaturization of an antenna decreases the performance of the antenna in terms of bandwidth. The smaller the dimensions of the antenna are made with respect to the wavelength of operation, to improve its integrability, the narrower its bandwidth BW becomes. Furthermore, the antenna has a quality coefficient Q that is inversely proportional to the bandwidth BW of the miniaturized antenna.
  • bandwidth By bandwidth, what is meant is the frequency range in which transfer of energy from the feed to the antenna or from the antenna to the receiver is maximized.
  • Bandwidth may be defined in terms of a criterion dependent on the reflection coefficient of the antenna. Below, the criterion “lower than ⁇ 6 dB” is chosen as limit of the reflection coefficient as a function of frequency to define bandwidth. This criterion is given merely by way of example.
  • quality factor Q what is meant is the parameter indicating the damping ratio of the antenna, equal to the ratio of the resonant frequency to the bandwidth.
  • the performance of the miniaturized antenna depends greatly on the electrical size of the antenna (size divided by the wavelength of operation).
  • the fundamental limits of antenna miniaturization have been the subject of much research for several decades.
  • the designer of a miniaturized antenna must find a compromise between the following three aims, because prioritizing one of the aims has an impact on the other two:
  • monopole “wire-patch” antennas are a possible compact omnidirectional-antenna solution suitable for many wireless-communication applications.
  • This type of antenna belongs both to the family of printed antennas and to the family of loaded monopole antennas.
  • these antennas are still the subject of much evolutionary and developmental work intending to increase their compactness and also to enlarge their operating band. This balance between miniaturization and performance must be achieved to keep up with increases in the throughput of data communicated between various systems and in the density of implementation of the hardware architectures of these systems.
  • prior-art miniaturized wire-patch antennas combine two resonant modes: a first resonance in the low-frequency domain with a frequency f 1 comprised between 0.7 GHz and 1 GHz (GSM band) and a resonance of the fundamental mode TM 01 at a frequency f 0 higher than 2 GHz.
  • the above demonstrates the need to produce miniaturized antennas in a way that allows an optimal compromise between enlargement of the bandwidth of the antenna, miniaturization and the quality of the radiation.
  • one technical problem to be solved is production of a miniaturized antenna allowing bandwidth to be enlarged without increasing the electrical dimensions of the antenna or degrading its quality factor.
  • the invention is applicable to radiocommunication devices of high integration density.
  • European patent EP3235058B1 describes a wire-patch antenna comprising a slot etched in its capacitive roof in order to enlarge the bandwidth of the antenna.
  • One drawback of the solution proposed in this patent is that the proposed antenna is no longer omnidirectional and changes the polarization of the electromagnetic field towards high operating frequencies.
  • the invention provides a plurality of embodiments of a wire-patch antenna having a new structure allowing the input impedance of the antenna to be matched so as to enlarge its bandwidth.
  • the solution according to the invention consists in modifying the input impedance of the antenna by means of simultaneous insertion of a parasitic capacitive element and of a parasitic inductive element. This geometric modification allows the spectral response of the antenna to be modified through excitation of an additional resonant mode. Excitation of two nearby resonant modes allows bandwidth in the targeted frequency range to be increased. In addition, this solution does not interfere with conventional higher printed-antenna modes, in particular the fundamental directional mode TM 01 .
  • This approach may be applied using various types of parasitic element, and it is particularly relevant to the family of monopole wire-patch antennas dedicated to various, especially GSM band, uplink and downlink mobile wireless communication systems.
  • the proposed structure according to the invention differs from known solutions especially in that it allows bandwidth to be enlarged in the low-frequency domain without degradation of the fundamental mode.
  • one advantage of the antenna according to the invention is that the technique is simple to implement.
  • the modified structure may be produced using commonplace manufacturing techniques, without the need for expensive modifications to the production line. An antenna with a low bulk and an enlarged bandwidth is achieved thereby. All of these advantages thus make the structure according to the invention a promising solution for applications in which multi-band, wideband and compact miniaturized antennas are employed.
  • One subject of the invention is a wire-patch antenna, comprising:
  • the end of the probe feed is separated from the capacitive roof by a volume of dielectric so as to create a parasitic capacitive element.
  • the parasitic capacitive element and the parasitic inductor form a parallel LC circuit allowing a second resonant mode to be excited at a second resonant wavelength shorter than the first resonant wavelength.
  • the distance of separation between the ground plane and the capacitive roof is comprised between one fiftieth of the first resonant wavelength and one tenth of the first resonant wavelength.
  • the distance of separation between the ground plane and the capacitive roof is comprised between one fiftieth of the first resonant wavelength and one fifteenth of the first resonant wavelength, or even one twentieth of the first resonant wavelength.
  • the capacitive roof is produced using a conductive layer forming a rectangular planar area with a width and/or length comprised between one tenth of the first resonant wavelength and one quarter of the first resonant wavelength.
  • the width and/or length of the impedance-matching wire is chosen depending on the value of the bandwidth defined by the first and second resonant modes.
  • the volume of dielectric separating the capacitive roof and the probe feed is a volume of air.
  • the impedance-matching wire is a metal rod.
  • the antenna further comprises a dielectric substrate such that:
  • the impedance-matching wire is a metal track deposited on the lower face of the substrate.
  • the short-circuiting wire is connected to the capacitive roof by way of a through-via that passes right through the substrate from its lower face to its upper face.
  • the substrate is confined between the end of the probe feed and the capacitive roof so as to produce the volume of dielectric.
  • the probe feed is inserted into the substrate by way of a non-through via starting from its lower face.
  • the short-circuiting wire and the probe feed are perpendicular to the ground plane and to the capacitive roof.
  • the antenna further comprises a discrete component connected in series or in parallel with the impedance-matching wire in order to adjust the value of the impedance of the parallel LC circuit.
  • Another subject of the invention is a geopositioning device intended to be integrated into a moving object comprising at least one wire-patch antenna according to the invention, said antenna being configured to transmit, to a remote server, via a communication system, the various positions of the moving object.
  • FIG. 1 shows a view of a cross section cut in the plane (x, z), illustrating a wire-patch antenna according to the prior art.
  • FIG. 2 shows a view of a cross section cut in the plane (x, z), illustrating a wire-patch antenna according to a first embodiment of the invention.
  • FIG. 3 shows a view of a cross section cut in the plane (x, z), illustrating a wire-patch antenna according to a second embodiment of the invention.
  • FIG. 4 shows a view of a cross section cut in the plane (x, z), illustrating a wire-patch antenna according to a third embodiment of the invention.
  • FIG. 5 shows a three-dimensional view illustrating a wire-patch antenna according to the second embodiment of the invention.
  • FIG. 6 shows a view from below of the substrate of the wire-patch antenna according to the second embodiment of the invention.
  • FIG. 7 a illustrates a plurality of curves of variation in the reflection coefficient of the wire-patch antenna as a function of frequency, each curve corresponding to one configuration of electrical connection of the impedance-matching wire.
  • FIG. 7 b illustrates a plurality of curves of variation in the real part of the input impedance of the wire-patch antenna as a function of frequency, each curve corresponding to one configuration of electrical connection of the impedance-matching wire.
  • FIG. 7 c illustrates a plurality of curves of variation in the imaginary part of the input impedance of the wire-patch antenna as a function of frequency, each curve corresponding to one configuration of electrical connection of the impedance- matching wire.
  • FIG. 8 illustrates a plurality of curves of variation in the reflection coefficient of the wire-patch antenna as a function of frequency, each curve corresponding to one width of the impedance-matching wire.
  • FIG. 9 illustrates a plurality of curves of variation in the reflection coefficient of the wire-patch antenna as a function of frequency, each curve corresponding to one length of the impedance-matching wire.
  • FIG. 10 illustrates a circuit diagram modelling the wire-patch antenna according to the invention.
  • FIG. 11 illustrates a three-dimensional radiation pattern of the wire-patch antenna according to the invention.
  • FIG. 12 illustrates a schematic of operation of a geopositioning device comprising a wire-patch antenna according to the invention.
  • FIG. 1 illustrates a view of a cross section cut in the plane (x, z) of a wire-patch antenna according to the prior art, said antenna being intended to be integrated into a radiocommunication system.
  • the wire-patch antenna 10 ′ comprises a ground plane 11 ′; a capacitive roof 12 ′; a probe feed 13 ′; and at least one electrically conductive short-circuiting wire 14 ′ linking the capacitive roof 12 ′ and the ground plane 11 ′.
  • the ground plane 11 ′ is formed by a metal layer and is linked electrically to the overall electrical ground of the system into which the antenna is integrated.
  • the ground plane may by way of example have rectangular, square or circular shapes.
  • the ground plane 11 ′ may be deposited on the upper face of a lower substrate (not shown).
  • the capacitive roof is formed by a metal layer placed parallel to the ground plane 11 ′ at a predetermined distance of separation.
  • the capacitive roof may by way of example have rectangular, square or circular in shapes.
  • the probe feed 13 ′ may be produced by extending the central conductor of a coaxial cable passing through the ground plane 11 ′ to the capacitive roof 12 ′.
  • the central conductor of the probe feed is connected at one end to a voltage generator (not shown) and at the other end to the capacitive roof 12 ′.
  • the central conductor of the probe feed 13 ′ is electrically isolated from the ground plane 11 ′, which is connected to the external shielding of the coaxial cable.
  • Combination of the probe feed 13 ′ with the capacitive roof 12 ′ placed facing the ground plane 11 ′ excites the fundamental resonant mode TM 01 of the antenna at a frequency f 0 .
  • the short-circuiting wire 14 ′ forms a metal return path to ground, provoking excitation of a first resonant mode in the low-frequency domain at a frequency f 1 lower than that of the fundamental mode f 0 .
  • the frequency f 1 of the “low-frequency wire-patch” mode is about half to one quarter of the frequency f 0 of the fundamental mode.
  • the short-circuiting wire 14 ′ may by way of example be produced using a metal rod of cylindrical or parallelepipedal shape.
  • the physical parameters that influence the frequencies f 0 and f 1 are the permittivity of the dielectric occupying the volume confined between the capacitive roof 12 ′ and the ground plane 11 ′, the distance between the capacitive roof 12 ′ and the ground plane 11 ′, the radius of the probe feed 13 ′, the radius of the short-circuiting wire 14 ′, the distance between the probe feed 13 ′ and the short-circuiting wire 14 ′, and the areal dimensions of the capacitive roof 12 ′ and the ground plane 11 ′.
  • the provided new wire-patch-antenna structure is intended to enlarge bandwidth in the vicinity of the frequency f 1 of the first resonant mode in the low-frequency domain without degrading the operation of the fundamental mode at f 0 and without increasing the dimensions of the various elements of the antenna, which dimensions were described in detail above.
  • the range containing frequencies below 1.5 GHz will be focused upon.
  • FIG. 2 illustrates a view of a cross section cut in the plane (x, z), illustrating a wire-patch antenna 10 according to a first embodiment of the invention.
  • the wire-patch antenna 10 comprises a ground plane 11 ; a capacitive roof 12 ; a probe feed 13 ; and at least one electrically conductive short-circuiting wire 14 linking the capacitive roof 12 and the ground plane 11 and at least one electrically conductive impedance-matching wire 15 electrically connecting the conductive short-circuiting wire 14 and the probe feed 13 .
  • the capacitive roof 12 rests mechanically on the rod forming the short-circuiting wire 14 , and the dielectric confined between the capacitive roof 12 and the ground plane 11 is air.
  • electrical insulator plastics for example
  • the probe feed 13 may be produced by passing the central conductor of a coaxial cable through the ground plane 11 to the capacitive roof 12 but stopping it short of touching said hat.
  • the central conductor of the probe feed 13 is electrically isolated from the ground plane 11 , which is connected to the external shielding of the coaxial cable.
  • the central conductor of the probe feed is connected at one end to a voltage generator (not shown) and at the other end stops short of the capacitive roof 13 at a second predetermined distance of separation H′.
  • the end of the probe feed 13 is separated from the capacitive roof 12 by a volume of dielectric so as to create a parasitic capacitive element C par .
  • the separating dielectric is air.
  • the parasitic capacitive element C par is thus series connected between the probe feed 13 and the capacitive roof 12 .
  • the value of the capacitance of the parasitic capacitive element C par depends on the permittivity of the material confined between the end of the probe and the hat, on the radius of the probe and on the second distance of separation H′.
  • the value of the inductance of the parasitic inductive element L par depends on the length of the wire and on its diameter in the case of a cylindrical rod for example.
  • the combination of the parasitic capacitive element C par and of the parasitic inductor L par forms a parallel LC circuit connected between the end of the probe feed 13 and the capacitive roof 12 .
  • This parallel LC circuit excites a second resonant mode in the low-frequency domain at a frequency f 2 close to the first frequency f 1 of the first resonant mode in the low-frequency domain.
  • the absolute value of the difference between the first frequency f 1 and the second frequency f 2 is comprised between 1.1 GHz and 1.5 GHz.
  • the short-circuiting wire 14 ′ still forms an active metal return path to ground, provoking excitation of the first resonant mode in the low-frequency domain at a frequency f 1 .
  • FIG. 3 illustrates a view of a cross section cut in the plane (x, z), illustrating a wire-patch antenna 10 according to a second embodiment of the invention.
  • the second embodiment employs the same concept, with addition of the impedance- matching wire 15 and separation of the end of the probe 13 from the capacitive roof 12 .
  • the antenna 10 of FIG. 3 further comprises a substrate sub 1 on which the capacitive roof 12 rests. This layer is producible using common deposition techniques, employed to obtain a copper layer that for example is 18 ⁇ m in thickness.
  • the substrate sub 1 may be a printed circuit board PCB.
  • the impedance-matching wire 15 may be produced by printing (or depositing) a metal track (or metal strip) on the lower face of the substrate sub 1 .
  • the substrate sub 1 thus performs a mechanical function in that it plays the role of carrier for the capacitive roof 12 and for the impedance-matching wire 15 .
  • the substrate sub 1 also performs an electrical function. Specifically, being confined between the upper end of the probe feed 13 and the lower face of the capacitive roof, the volume of dielectric of the parasitic capacitor C par is formed with the substrate sub 1 . Regarding the volume of dielectric between the capacitive roof 12 and the ground plane 11 , it remains mainly filled with air given the small thickness of the substrate sub 1 with respect to the first distance of separation H.
  • the short-circuiting wire 14 is connected to the capacitive roof 12 by way of a through-via V 1 that passes right through the substrate sub 1 from its lower face to its upper face, on which face the capacitive roof 12 rests.
  • FIG. 4 shows a view of a cross section cut in the plane (x, z), illustrating a wire-patch antenna 10 according to a third embodiment of the invention.
  • the third embodiment employs the same concept, with addition of the impedance-matching wire 15 and separation of the end of the probe 13 from the capacitive roof 12 .
  • the antenna 10 of FIG. 3 further comprises a substrate sub 1 on which the capacitive roof 12 rests, in the same way as the second embodiment.
  • the third embodiment differs from the second embodiment in that the thickness of the substrate is larger.
  • the substrate sub 2 is not confined between the upper end of the probe feed 12 but occupies a larger proportion of the volume bounded by the capacitive roof 12 and the ground plane 11 .
  • the substrate sub 2 comprises a first through-via V 1 containing one portion of the short-circuiting wire 14 extending as far as the capacitive roof 12 .
  • the substrate sub 2 further comprises a second non-through via V 2 that starts from its lower face but that does not open onto the interface of the substrate sub 2 with the capacitive roof 12 .
  • the upper portion of the probe feed 12 is then inserted into the non-through via V 2 .
  • the volume of the substrate sub 2 confined between the upper end of the probe feed 13 and the lower face of the capacitive roof 12 forms the dielectric of the capacitive element C par .
  • the dielectric that forms the substrate sub 2 must be chosen such that its electrical permittivity is limited, and for example lower than 6, and preferably equal to 2, in order not to alter the electromagnetic behaviour of the antenna.
  • the impedance-matching wire 15 by printing (or depositing) a metal track (or metal strip) on the lower face of the substrate sub 2 .
  • the substrate sub 2 thus performs a mechanical function in that it plays the role of carrier for the capacitive roof 12 and for the impedance-matching wire 15 .
  • the substrate sub 2 also performs an electrical function, forming as it does the dielectric of the capacitive element C par .
  • the substrate sub 2 occupies the entire height H separating the capacitive roof 12 and the ground plane 11 .
  • the impedance-matching wire 15 is confined in the substrate sub 2 .
  • the first, second or third embodiment comprises a plurality of short-circuiting wires 14 and a plurality of impedance-matching wires 15 .
  • a plurality of impedance-matching wires 15 allows an adjustable connection to be made between the probe feed 13 and one or more short-circuiting wires 14 .
  • FIG. 5 illustrates a three-dimensional view illustrating a wire-patch antenna according to the second embodiment of the invention.
  • the capacitive roof 12 of the antenna is a square metal layer deposited on the substrate sub 1 , which is a PCB substrate.
  • the dimensions of the capacitive roof 12 are as follows: thickness 18 ⁇ m and side length of ⁇ 1 /6 with ⁇ 1 the wavelength associated with the first resonant mode in the low-frequency domain (915 MHz).
  • the capacitive roof 12 is suspended at a height of A 1 /17.6 above the ground plane 11 .
  • the capacitive roof 11 may be produced on a printed circuit board in which the upper and lower layers are etched with the desired patterns.
  • the short-circuiting wire 14 allowing the first low-frequency monopole mode to be excited is placed at the centre of the capacitive roof 12 . It is a question of a metal rod that may be cylindrical, parallelepipedal or pyramidal.
  • the geometry of the probe feed 13 and its distance with respect to the short-circuiting wire 14 are dimensioned to excite the fundamental mode TM 01 about 2.45 GHz and the first resonant mode in the low-frequency domain of 915 MHz.
  • the distance between the probe feed 13 and the short-circuiting wire 14 is 18 mm—corresponding to ⁇ 1 /18.5.
  • the probe feed is composed of a rod of cylindrical shape that is ⁇ 1 /22.2 in height and the radius of which has been adjusted to guarantee a good impedance match at the operating frequencies of the antenna.
  • the impedance-matching wire 15 is a metal strip that is deposited on the lower face of the substrate sub 1 and that links the upper end of the probe feed 13 to the short-circuiting wire 14 . It is a question of a copper track of width comprised between 2 mm and 3 mm and of length comprised between 18 mm and 35 mm.
  • the impedance-matching wire 15 allows a second resonant mode to be excited near the resonant mode in the low-frequency domain, allowing bandwidth BW to be enlarged in the frequency range z.
  • the ground plane 11 is a square metal layer having an area larger than that of the capacitive roof 13 .
  • the distance H separating the capacitive roof 12 from the ground plane 11 varies inversely to the areal dimensions of the capacitive roof 12 .
  • the distance H separating the capacitive roof 12 from the ground plane 11 is increased, the side length of the square of the capacitive roof 12 must be decreased, and vice versa. It is possible to choose, for the distance H separating the capacitive roof 12 from the ground plane 11 , a value comprised between ⁇ 1 /50 and ⁇ 1 /10.
  • the side length of the square defining the area of the capacitive roof 12 is set equal to ⁇ 1 /10.
  • the side length of the square defining the area occupied by the capacitive roof 12 is set equal to ⁇ 1 /4. This rule is tailored to the shape chosen for the area occupied by the capacitive roof 12 (radius for a circular area, width and length for a rectangle).
  • FIG. 6 illustrates a view from below of the substrate of the wire-patch antenna according to the second embodiment of the invention, in order to show how the impedance-matching wire 15 deposited on the lower face of the substrate sub 1 is implemented.
  • the inductance of the parasitic inductive element L par depends on the length L and width W of the metal strip deposited to produce the impedance-matching wire 15 . Increasing L increases the inductance of the parasitic inductive element L par and vice versa.
  • Schematic 61 illustrates an impedance-matching wire 15 produced with a U-shaped metal strip linking the probe feed 13 to the short-circuiting wire 14 .
  • Use of a U shape provides the designer with a degree of freedom allowing the length L to be chosen without modifying the position of the probe feed 13 with respect to the short-circuiting wire 14 .
  • the distance between the probe feed 13 and the short-circuiting wire 14 must remain unchanged in order not to alter the fundamental resonance at 2.45 GHz.
  • Schematic 62 illustrates two impedance-matching wires 15 each produced with a U-shaped metal strip linking the probe feed 13 to the short-circuiting wire 14 .
  • the two impedance-matching wires are placed symmetrically with respect to the straight line joining the upper end of the probe feed 13 and the upper end of the short-circuiting wire 14 .
  • the two impedance-matching wires have the same length L and the same width W and thus form the equivalent of a wire having a length equal to L and a width larger than 2 ⁇ W.
  • Use of this double metal strip provides the designer with a degree of freedom allowing the width W of the equivalent impedance-matching wire to be increased without exceeding the limits in terms of width W set by the constraints of the process used to manufacture the metal tracks.
  • FIG. 7 a illustrates a plurality of curves of variation in the reflection coefficient of the wire-patch antenna as a function of frequency, each curve corresponding to one configuration of electrical connection of the impedance-matching wire.
  • Curve C 0 corresponds to a wire-patch antenna without impedance-matching wire 15 .
  • Curve C 1 corresponds to a wire-patch antenna with an impedance-matching wire 15 touching at one end the short-circuiting wire 14 and at the other end the probe feed 13 .
  • Curve C 2 corresponds to a wire-patch antenna with an impedance-matching wire 15 solely touching the short-circuiting wire 14 .
  • Curve C 3 corresponds to a wire-patch antenna with an impedance-matching wire 15 solely touching the probe feed 13 .
  • Curve C 4 corresponds to a wire-patch antenna with an impedance-matching wire 15 placed in proximity to the probe feed 13 and the short-circuiting wire 14 but not touching them.
  • FIG. 7 b illustrates a plurality of curves of variation in the real part of the input impedance of the wire-patch antenna as a function of frequency, each curve corresponding to one configuration of electrical connection of the impedance-matching wire.
  • Curve C′ 1 corresponds to a wire-patch antenna with an impedance-matching wire 15 touching at one end the short-circuiting wire 14 and at the other end the probe feed 13 .
  • Curve C′ 2 corresponds to a wire-patch antenna with an impedance-matching wire 15 solely touching the short-circuiting wire 14 .
  • Curve C′ 3 corresponds to a wire-patch antenna with an impedance-matching wire 15 solely touching the probe feed 13 .
  • Curve C′ 4 corresponds to a wire-patch antenna with an impedance-matching wire 15 placed in proximity to the probe feed 13 and the short-circuiting wire 14 but not touching them.
  • FIG. 7 c illustrates a plurality of curves of variation in the imaginary part of the input impedance of the wire-patch antenna as a function of frequency, each curve corresponding to one configuration of electrical connection of the impedance-matching wire.
  • Curve C′′ 1 corresponds to a wire-patch antenna with an impedance-matching wire 15 touching at one end the short-circuiting wire 14 and at the other end the probe feed 13 .
  • Curve C′′ 2 corresponds to a wire-patch antenna with an impedance-matching wire 15 solely touching the short-circuiting wire 14 .
  • Curve C′′ 3 corresponds to a wire-patch antenna with an impedance-matching wire 15 solely touching the probe feed 13 .
  • Curve C′′ 4 corresponds to a wire-patch antenna with an impedance-matching wire 15 placed in proximity to the probe feed 13 and the short-circuiting wire 14 but not touching them.
  • Curve C 0 which corresponds to an antenna without impedance-matching wire, indicates a narrow bandwidth BW 0 in the vicinity of the frequency f 1 of the first low-frequency monopole resonant mode.
  • curve C′ 0 the frequency range in which the real part of the impedance is close to 50 ⁇ in the vicinity of f 1 is very narrow. This shows the limits of a wire-patch antenna without insertion of an impedance-matching wire 15 in terms of bandwidth.
  • curve C 1 illustrates that, when the impedance-matching wire 15 is connected both to the probe feed 13 and to the short-circuiting wire 14 , a bandwidth BW 1 larger than the initial bandwidth BW 0 is obtained. This bandwidth is located in the targeted frequency range [0.5 GHz, 1.5 GHz].
  • Curve C′ 1 indicates the appearance of a second resonant mode at a frequency f 2 of about 1.1 GHz. A shift in the first resonant mode is also observed, its frequency passing from f 1 to f′ 1 . The shift in the first “wire-patch resonant” mode is 100 MHz towards low frequencies.
  • This double-resonance effect allows a frequency range in which impedance remains stable at about 50 ⁇ in the real part of the input impedance to be created between the two resonant peaks at f′ 1 (associated with ⁇ ′1, which is almost equal to ⁇ 1) and f 2 (associated with ⁇ 2). It is this frequency range that is used to widen the band. It is thus possible to enlarge the bandwidth of the antenna without increasing the size of the wire-patch antenna or degrading its quality factor.
  • FIG. 8 illustrates a plurality of curves of variation in the reflection coefficient of the wire-patch antenna as a function of frequency, each curve corresponding to one impedance-matching-wire width.
  • FIG. 9 illustrates a plurality of curves of variation in the reflection coefficient of the wire-patch antenna as a function of frequency, each curve corresponding to one impedance-matching-wire length.
  • FIG. 10 illustrates a circuit diagram modelling the wire-patch antenna according to the invention. Specifically, it is possible to model the antenna according to the invention electrically in the following way:
  • the capacitive element C toit and the inductive element L cc together form a parallel circuit L cc C toit placed between the electrical node N toit associated with the capacitive roof 12 and the electrical node N masse associated with the ground plane 11 .
  • the parallel circuit L cc C toit is used to excite the first low-frequency resonant mode at f′ 1 .
  • the parasitic capacitive element C par and the parasitic inductive element L par together form a parallel circuit L par C par placed between the electrical node N sonde associated with the end of the implementation probe 13 and the electrical node N toit associated with the capacitive roof 12 .
  • the parallel circuit L par C par is used to excite the second resonant mode in the low-frequency domain at f 2 .
  • the dimensions of the antenna are chosen to obtain a pair of frequencies f′ 1 and f 2 that are quite close together, so as to obtain a wide bandwidth in the low-frequency range of operation.
  • f′ 1 and f 2 frequencies f′ 1 and f 2 that are quite close together, so as to obtain a wide bandwidth in the low-frequency range of operation.
  • quite close together what is meant is a frequency difference comprised between 1.1 GHz and 1.5 GHz absolute value.
  • the new resonance may also be adjusted to f 2 by adding a discrete component or an adjustable component in series or parallel with the parasitic track in order to adjust the central frequency of the bandwidth obtained via the combination of f′ 1 and f 2 .
  • discrete component what is meant is a basic electronic component the role of which is to perform an elementary function. In the context of the invention, this term covers passive discrete components such as inductors, capacitors, and resistors.
  • FIG. 11 illustrates a three-dimensional radiation pattern of the wire-patch antenna according to the invention.
  • the wire-patch antenna according to the invention has the advantage of an omnidirectional radiation pattern, as illustrated in FIG. 11 . More precisely, the figure illustrates the pattern in three dimensions of the gain achieved in the GSM band (at 917 MHz). The efficiency of the antenna is higher than 60% over a band of 80 MHz width corresponding to 10% of the relative band.
  • FIG. 12 illustrates a schematic diagram of operation of a geopositioning device comprising a wire-patch antenna according to the invention.
  • the geopositioning device 100 is intended to be integrated into a moving object such as a vehicle, a mobile telephone, or a smart watch, these examples being non-limiting.
  • the geopositioning device comprises at least one wire-patch antenna 10 according to the invention.
  • the antenna 10 is configured to transmit, to a remote server 110 , via a communication system 120 , the various positions of the moving object.
US18/086,812 2021-12-23 2022-12-22 Monopole wire-patch antenna with enlarged bandwidth Pending US20240030610A2 (en)

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FR2114355A FR3131463B1 (fr) 2021-12-23 2021-12-23 Antenne fil plaque monopolaire à bande passante élargie
FR2114355 2021-12-23

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KR100680728B1 (ko) * 2005-03-16 2007-02-09 삼성전자주식회사 수직 접지면을 갖는 전자기적 결합 급전 소형 광대역 모노폴 안테나
FR3030909B1 (fr) 2014-12-19 2018-02-02 Commissariat A L'energie Atomique Et Aux Energies Alternatives Antenne fil-plaque ayant un toit capacitif incorporant une fente entre la sonde d'alimentation et le fil de court-circuit
FR3070224B1 (fr) * 2017-08-18 2020-10-16 Sigfox Antenne plaquee presentant deux modes de rayonnement differents a deux frequences de travail distinctes, dispositif utilisant une telle antenne
CN110350308B (zh) * 2019-07-15 2020-12-18 重庆大学 一种超宽带低剖面垂直极化全向天线及其陷波设计方法

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EP4203189A1 (de) 2023-06-28

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