WO2006036116A1 - Antenne en anneau - Google Patents

Antenne en anneau Download PDF

Info

Publication number
WO2006036116A1
WO2006036116A1 PCT/SE2005/001418 SE2005001418W WO2006036116A1 WO 2006036116 A1 WO2006036116 A1 WO 2006036116A1 SE 2005001418 W SE2005001418 W SE 2005001418W WO 2006036116 A1 WO2006036116 A1 WO 2006036116A1
Authority
WO
WIPO (PCT)
Prior art keywords
antenna
hole
corners
antenna according
contour
Prior art date
Application number
PCT/SE2005/001418
Other languages
English (en)
Inventor
Tomas Rutfors
Original Assignee
Tomas Rutfors
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
Application filed by Tomas Rutfors filed Critical Tomas Rutfors
Publication of WO2006036116A1 publication Critical patent/WO2006036116A1/fr

Links

Classifications

    • 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
    • H01Q9/16—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole
    • H01Q9/26—Resonant 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
    • 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
    • H01Q9/16—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole

Definitions

  • the present invention concerns an antenna for wireless communications .
  • the antenna is a plane antenna above a ground plane which commonly is termed patch antennas.
  • the invention also concerns antennas with circular polarisation which are common in both stationary and satellite communications.
  • an antenna is to convert wire bound signals to electromagnetic signals propagating in the ambient media.
  • the design of the antenna determines the properties of this conversion. Important parameters are antenna gain, efficiency, directionality, polarisation, bandwidth and not least physical size.
  • the requirements of a wireless communication system determine the requirements of the antenna and by that what type of antenna to be used.
  • the antenna can be optimised for this application. Because more applications are using wireless communications indoors both aesthetical requirements and radio requirements, due to the large attenuation and radio signal reflections in walls for instance, apply.
  • Plane antennas that can be placed directly on objects such as walls have become very common.
  • One type of plane antenna is the so called patch antenna. It consists of a layer or surface of an electrically conductive material with a very small thickness compared to other dimensions that is placed a distance, which is small compared to the wavelength, above and in parallel with a ground plane.
  • the signal to be emitted is coupled to the antenna element and the ground plane is coupled to the return conductor of the signal or ground. Since the antenna has a ground plane on one side, this side can be placed on objects without appreciably affecting its function and performance. The drawback is that its surface becomes relatively large.
  • the sides of a conventional quadratic patch antenna correspond to approximately H wavelength of the lowest frequency that can be emitted, which for an antenna for 1 GHz corresponds to 17 cm. That results in it becoming unwieldy and large, in particular for frequencies below 1 GHz.
  • a hole can be made in a patch to reduce the size.
  • This type of antenna is usually called a ring antenna.
  • the hole can be made in both circular and rectangular patch antennas.
  • This antenna is also popular owing to that it can be made with either linear or circular polarisation.
  • the hole is placed centrally in the patch, and by increasing the size of the hole, the frequency of the antenna is reduced. If the outer contour is deformed by cuttings of a specified size +45 and -135 degrees from a line that intersects the centre of the antenna and the feed spot, the antenna will generate a circularly polarised signal. This is due to two different modes TMi 0 and TM 0I are generated with a small frequency shift and 90 degrees phase shift in relation to each other.
  • the resonant frequency will be lowered but the impedance of the antenna at the resonant frequency will be increased, which makes matching to the system impedance 50 ohms more difficult. If the hole is enlarged so that the width of the conducting material is decreased, the properties of the patch will resemble a short circuited loop antenna, the total length of which is one wavelength, making the length of each side a quarter of a wavelength.
  • a short circuited loop antenna has very high impedance at its resonant frequency which limits its application.
  • the present invention makes it possible to lower the resonant frequency of a ring antenna, without increasing its size, and also to, in a simple way, being able to adjust the impedance of the antenna to the system impedance of 50 ohms.
  • the present invention concerns a plane antenna element having a centred hole.
  • the outer contour of the antenna has a substantially rectangular or quadratic shape and the contour of the hole differs from rectangular or quadratic shape.
  • the antenna element is placed a distance above, and in a plane in parallel with, a ground plane.
  • the ground plane is as large as or larger than the antenna.
  • the resonant frequency can be lowered without increasing the impedance at resonance.
  • the extension should be designed in a way so that the area of the hole is less than for corresponding rectangular or quadratic holes.
  • the impedance of the antenna can be changed without appreciably changing the resonant frequency of the antenna.
  • the extension should be designed in a way that the area of the hole is less than the area of corresponding rectangular or quadratic holes. This adjustment both simplifies the adjustment of the antenna to the system impedance of 50 ohms and gives the possibility of moving the feed spot of the antenna closer the centre of the antenna, which in turn affects the impedance so as to simplify matching.
  • the antenna By changing radii or bevelling of two of the diagonal corners of the hole, the antenna becomes circularly polarised.
  • Figure 1 illustrates a general patch antenna from above.
  • Figure 2 illustrates a general patch antenna with lead-through of a radio signal through a hole in the ground plane of the antenna.
  • Figure 3 illustrates a general patch antenna with connection of a radio signal from one side.
  • Figure 4 illustrates how according to the invention the extension of the contour of the hole may be designed to achieve a lower resonant frequency.
  • Figure 5 illustrates quantitatively the size of change in resonant frequency that can be obtained when the extension of the contour is increased.
  • Figure 6 illustrates an alternative geometrical design of the extension of the contour.
  • Figure 7 illustrates how the contour of the antenna can be changed to obtain the resonant frequency with a change in impedance that allows a simple matching to 50 ohms.
  • Figure 8 illustrates in a Smith-diagram how the invention helps impedance matching.
  • Figure 9 illustrates how the invention may be designed to provide circular polarisation.
  • Figure 10 illustrates that the invention allows for all four contours to be extended and that the feed spot also can be moved closer to the centre, if needed.
  • a patch antenna that is general and commonly known is illustrated.
  • a patch antenna consists of an antenna element 11 that has a spot 13 where the radio signal that is sent from the transmitter or that is to be received by the receiver is connected.
  • the antenna element has the size Xp and Yp that provide the antenna with a certain resonant frequency, i.e. the frequency where the antenna may send or receive electromagnetic signals effectively.
  • the antenna element that is made of an electrically conductive material for example copper, aluminium, brass, gold, has a ground plane 10 of conductive material that is located a distance from and substantially in parallel with said antenna.
  • the ground plane is as large as or larger than the antenna and covers the whole area of the antenna according to figure 1.
  • Figure 2 and 3 illustrates a general and commonly known patch antenna from one side.
  • the antenna element 11 lies a distance h from the ground plane 10.
  • the antenna and ground plane are separated by an electrical insulator 12.
  • the insulator may be of different materials such as plastics of different kinds, ceramic materials or substrates that are used for electrical printed circuit cards.
  • the isolator may also be air or other gases .
  • the dielectric properties of the isolator will affect the resonant frequency of the antenna.
  • the radio signal 13 is sent through a hole 14 in the ground plane.
  • the ground plane 10 is connected to the transmission line of the radio signal.
  • the radio signal 13 is sent to the antenna element via a connection wire 15 to a defined spot on the antenna element.
  • the ground plane must be connected to the transmission line via 10b.
  • the antenna In figure 4 and onward only the antenna element is shown for simplicity. However, the antenna must have a ground plane and feeding according to figure 1 through 3 or in other ways that are commonly known.
  • Figure 4 illustrates how the rectangular hole should be modified to lower the resonant frequency of the antenna.
  • the extensions When the feed spot 20 is placed between the corners 30 and 33 of the hole, the extensions should be placed between the corners 30, 31 and 32, 33 respectively.
  • the extensions may be of different length 35 and 36 and different width 37 and 38. If the length is increased the resonant frequency will be lowered.
  • FIG 5 is shown quantitatively how much an extension of the contour of the hole on the sides between the corners 30, 31 and 32, 33 respectively lowers the resonant frequency for a rectangular ring antenna.
  • Y corresponds to the width 37 and 38 on the contour that has a rectangular shape.
  • the width is fixed at 6 mm.
  • the length X corresponds to 35 and 36 and is increased equally from both sides in some steps from 0 to 10 mm.
  • the total size of the antenna element is 34 x 34 mm and the size of the hole is 22 x 22 mm.
  • the antenna element is located 4 mm above a ground plane with the size 40 x 40 mm.
  • the lowering of resonant frequency corresponds to 10 % compared to a corresponding ring antenna without extensions of the contour of the hole.
  • Figure 6 illustrates an alternative geometry that comes within the scope of the invention. All geometries that increase the length of the contour and at the same time decreases the area of the hole compared to the rectangular or quadratic hole comes within the scope of the invention.
  • Figure 7 illustrates how the invention solves the problem of matching the impedance to 50 ohms for ring antennas with large holes.
  • the extension of the contour and by that the increase in antenna area in the vicinity of the feed spot and/or -on the opposite side of the antenna, can have an arbitrary geometrical shape.
  • the impedance at the spot 50 By increasing the surfaces 40 and 41 with a fixed area, the impedance at the spot 50, according to figure 8, will be transferred from the spot 70 along 71 to 72.
  • the impedance according to figure 8 By connecting an inductor 51 with correct inductance between the connection spot 50 of the radio signal and the feed spot 20 of the antenna and then to earth, the impedance according to figure 8 will go along 73 to the spot 74 that corresponds to 50 ohms. In this way, it is possible to match the antenna to the impedance 50 ohms.
  • the inductor 51 may for instance be a coil, a printed- pattern on a printed circuit card, one or more electrical conductors of fixed length.
  • the inductor may also be constructed in other ways.
  • Figure 9 illustrates how the antenna element can be changed to send or receive circularly polarised electromagnetic fields. Because the corners 30 and 32 of a diagonal 60 have a fixed radius or bevelling that differs a fixed amount from the radius or bevelling of the corners 31 and 33 of the opposite diagonal 61, a circular polarisation of the emitted signal from the antenna is achieved. Since an antenna is reciprocal, it also receives electromagnetic fields with the same circular polarisation. Since a circular polarisation consists of two orthogonal linear signals that are shifted in phase with + 90 degrees or - 90 degrees, the antenna also receives linearly polarised signals.
  • Figure 10 illustrates an example of how an antenna may look like having combined extensions of all four contours to both achieve a small size in relation to desired resonant frequency and correct matching to the system impedance of 50 ohms .
  • the radio signal is coupled via an electrical conductor to the antenna element.
  • the conductor as the man skilled in the art realizes, may be coupled to the antenna element with direct or indirect coupling.
  • direct coupling an electrical conductor is understood, and by indirect coupling a capacitive or inductive coupling is understood.

Landscapes

  • Waveguide Aerials (AREA)

Abstract

L'invention porte sur une antenne d'un système de communications sans fil pourvu d'un élément essentiellement plan formé dans un matériau électroconducteur, cette antenne étant placée à une distance au-dessus d'un plan de masse d'un matériau électroconducteur et en parallèle avec celui-ci, l'élément d'antenne comportant un trou central. Le trou de l'élément d'antenne est étendu sur quatre angles et représente une forme sensiblement rectangulaire, et un ou plusieurs des bords du trou est courbe et, de ce fait, ces bords ont un contour étendu, le trou ayant une surface plus petite, mais un contour plus long que le trou correspondant, avec des lignes droites entre les quatre angles. Le signal radio est envoyé via un conducteur électrique couplé à l'élément d'antenne, et le retour du signal passe par un conducteur électrique couplé au plan de masse.
PCT/SE2005/001418 2004-09-27 2005-09-27 Antenne en anneau WO2006036116A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0402333-9 2004-09-27
SE0402333A SE0402333D0 (sv) 2004-09-27 2004-09-27 Ringantenn

Publications (1)

Publication Number Publication Date
WO2006036116A1 true WO2006036116A1 (fr) 2006-04-06

Family

ID=33414834

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2005/001418 WO2006036116A1 (fr) 2004-09-27 2005-09-27 Antenne en anneau

Country Status (2)

Country Link
SE (1) SE0402333D0 (fr)
WO (1) WO2006036116A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102011117690B3 (de) * 2011-11-04 2012-12-20 Kathrein-Werke Kg Patch-Strahler
WO2013064204A1 (fr) 2011-11-04 2013-05-10 Kathrein-Werke Kg Élément rayonnant "patch"
DE102012016627A1 (de) 2012-08-22 2014-02-27 Kathrein Werke Kg Patch-Strahler

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5410323A (en) * 1992-04-24 1995-04-25 Sony Corporation Planar antenna
US20040061648A1 (en) * 2001-02-07 2004-04-01 Pros Jaume Anguera Miniature broadband ring-like microstrip patch antenna

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5410323A (en) * 1992-04-24 1995-04-25 Sony Corporation Planar antenna
US20040061648A1 (en) * 2001-02-07 2004-04-01 Pros Jaume Anguera Miniature broadband ring-like microstrip patch antenna

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102011117690B3 (de) * 2011-11-04 2012-12-20 Kathrein-Werke Kg Patch-Strahler
WO2013064204A1 (fr) 2011-11-04 2013-05-10 Kathrein-Werke Kg Élément rayonnant "patch"
US9647328B2 (en) 2011-11-04 2017-05-09 Kathrein-Werke Kg Patch radiator
DE102012016627A1 (de) 2012-08-22 2014-02-27 Kathrein Werke Kg Patch-Strahler

Also Published As

Publication number Publication date
SE0402333D0 (sv) 2004-09-27

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