WO2007141505A1 - A patch antenna - Google Patents
A patch antenna Download PDFInfo
- Publication number
- WO2007141505A1 WO2007141505A1 PCT/GB2007/002052 GB2007002052W WO2007141505A1 WO 2007141505 A1 WO2007141505 A1 WO 2007141505A1 GB 2007002052 W GB2007002052 W GB 2007002052W WO 2007141505 A1 WO2007141505 A1 WO 2007141505A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- antenna
- patch
- edge
- capacitors
- layer
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/12—Supports; Mounting means
- H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
- H01Q1/2208—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems
- H01Q1/2225—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
-
- 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
- H01Q9/0442—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with particular tuning means
Definitions
- the present invention relates to antenna technology, and in particular, but not exclusively to a patch antenna.
- Digital communications have become essential in the modern age in which data is transmitted between various locations around the world. hi particular, the field of wireless communications has exploded especially in the area of mobile phone communications and/or other wireless computer-related devices. Indeed, such has been the growth of wireless communications, specifically RF-type wireless communications, that the frequency spectrum for transmitting radio waves is becoming increasingly crowded.
- RP Radio Frequency
- the RP designer must try and select the type of antenna whose properties are most suitable for the relevant application. For example, for a mobile phone application the RF designer will typically look for a compact antenna design having a low-power properties that occur when size, weight and portability are important as they are in the wireless field.
- RPID radio frequency identification
- an antenna possessing certain properties for example: small in size, a low profile and lightweight.
- Such antennas can be used as transmitters, receivers or transceivers that can be easily attached to a package or other moveable asset to be tracked.
- a micro strip antenna is often most suitable.
- a micro strip antenna is often referred to as a patch antenna since it consists of a patch of metallisation overlying, yet separated from, a ground plate.
- a patch antenna is often manufactured by etching an antenna element pattern in a metal trace that is bonded to an insulating substrate which separates the ground plate from the etched antenna element.
- Other advantages of such antennas is that they are easy to manufacture and mechanically rugged.
- patch antennas have the ability for polarisation diversity.
- a further concept in antenna technology is the idea of a so-called “electrically short antenna", in which the electrical conductor of the antenna is physically short in length and often significantly shorter than the wavelength of the resonating frequency of the antenna.
- the advantage of such short antennas is a reduction in size, which is particularly useful in the field of RFK) tags or identifier antennas.
- microstrip patch antennas are still required to be of a certain size to transmit at a particular resonating frequency. It is especially desirable to reduce the size of such antennas that are attached to assets for tracking purposes.
- an antenna for communicating data comprises a dielectric layer that separates an electrically grounded layer from a conductor layer, wherein the conductor layer has a first portion connected to a capacitive element
- the capacitive element makes the patch antenna looking electrically longer than it physically is. This means that the size of the antenna can be reduced, while still operating at the same frequency.
- a further advantage is that it is possible to vary the operating frequency of the antenna in an inversely proportional manner to the value of the capacitive element.
- the capacitive element is a plurality of capacitors.
- the plurality of capacitors are evenly spaced producing a more uniform electromagnetic field radiated from the edge of the antenna.
- the first portion is a first edge of a rectangular patch antenna.
- the conductor layer has a second portion that is connected to the ground plate.
- the antenna forms part of an RFID tag attached to an object such that movements of the object can be tracked.
- a rectangular patch antenna comprising: a ground plate that is electrically grounded; a conduction layer having electrical conductors; a dielectric layer for separating the ground plate from the conduction layer; and wherein the conduction layer having a first edge connected to the ground layer and a second edge having a plurality of capacitors for enhancing the edge capacitance.
- a rectangular patch antenna comprising: a ground plate that is electrically grounded; a conduction layer having electrical conductors; a dielectric layer for separating the ground plate from the conduction layer; and wherein the conduction layer having a first and a second radiating edge that each have a plurality of capacitors for enhancing their respective edge capacitance.
- Figures 1 shows a plan view of a basic patch antenna
- Figure 2 shows a side view of the patch antenna
- Figure 3 shows a perspective view of a patch antenna according to a first embodiment
- Figure 4 shows a plot of the desired frequency response of the antenna
- Figure 5 shows an impedance graph of the antenna
- Figure 6 shows a perspective view with defined dimensions of the antenna according to the first embodiment
- Figure 7 shows a side view with the electromagnetic field according to the first embodiment
- Figure 8 shows an equivalent transmission line circuit according to the first embodiment
- Figure 9 shows a perspective view of the patch including the capacitors according to the first embodiment
- Figure 10 shows a perspective view with defined dimensions of the antenna according to an alternative embodiment
- Figure 11 shows a side view with the electromagnetic field of the alternative embodiment
- Figure 12 shows an equivalent transmission line circuit of the alternative embodiment
- Figure 13 shows a perspective view of the patch including the capacitors for the alternative embodiment
- Figures 14a shows the reduction in patch size when no capacitance is added to the edges.
- Figure 14b shows the reduction in patch size when capacitance is added.
- Figure 1 shows a plan view of a basic patch antenna
- Figure 2 shows a side view of the antenna.
- the patch antenna shown in Figure 1 has a circular shape, but it should be appreciated that other shapes of patch antenna are possible, for example a square or a rectangular shape.
- Figure 3 shows patch antenna according to a preferred embodiments of the present inventions comprising a rectangular shape.
- Figures 1 and 2 show a patch antenna has an underlying ground plate element 100, a dielectric layer 140 located on the ground plate, and a conduction layer 110 located on the dielectric layer.
- the patch antenna is usually printed on a circuit board and has a radiation pattern in any direction above the ground plane in a hemispherical area.
- the thickness of the dielectric layer 140 determines the conduction layer 110 separation from ground 100, which effects the bandwidth of the patch antenna. Generally, the thicker the dielectric layer, the higher the bandwidth.
- the resonating frequency at which the antenna operates increases as the antenna size is reduced.
- FIG. 3 shows an exploded view of the geometry of a patch antenna according to a preferred embodiment of the present invention.
- the electrical short patch antenna is a rectangular patch antenna having a ground plate 300, with a separating dielectric substrate 340 and a top printed layer 310.
- the top layer 310 comprises the conductor arrangement 320 of the antenna.
- Figure 3 shows that one edge 350 of the top layer 310 has vias which are able to be electrically connected to the ground plate 300.
- metallic vias can placed in respective holes formed in the dielectric layer to connect one edge 350 of the top conduction layer 310 to the ground plate 300, effectively shorting that edge of the antenna to ground.
- the top layer 310 additionally is also shown as comprising a plurality of capacitors, Cl, C2, C3, C4, C5 and C6 located along the opposite edge 360 of the top layer. These capacitors increases the edge capacitance of the patch antenna.
- the plurality of capacitors Cl to C6 shown in Figure 3 are connected in parallel.
- each of the capacitors Cl to C6 is connected to the patch by having one plate of each capacitor grounded and the other plate connected to the conduction layer 310.
- Each plate of the capacitor may be grounded by connecting the plate to a relevant via, which is fitted through a relevant hole 395 (see for example Figures 9 and 13) in the dielectric layer, and connects to the ground plate 300.
- the capacitors Cl to C6 are located on the same side of the patch as the RF feed point 370.
- the capacitors are spaced equally along the feed point 370 edge of the patch surface.
- There is more than one capacitor on each side of the feedpoint such that current is distributed uniformly along the edge 360 of the patch antenna. This advantageously allows an even electromagnetic field distribution for the antenna.
- the dielectric layer 340 being of a thickness of 1.6mm and having an RF feedpoint that is located using impedance matching.
- Figures 6 to 9 shows an embodiment in which one edge of the conduction layer 310 is shorted to the ground plate (as shown in the embodiment of Figure 3), whereas Figures 10 to 13 show an alternative embodiment in which both of the opposing edges have capacitors connected (i.e. no edge is grounded).
- Figure 6 shows a perspective view of the patch antenna embodiment of Figure 3 with one edge shorted.
- Figure 6 defines various dimensions such as the length L and Width W of the conduction layer 310, as well as the thickness h of the dielectric layer 340.
- Figure 7 shows a side view of the antenna embodiment shown in figure 3 and in particular shows that one side is shorted to ground, whereas on the other side fringing fields give rise to an edge capacitance that is responsible for the radiated field.
- Figure 7 also illustrates the distribution of the electromagnetic field under the patch antenna. By adding lumped capacitors to the edge that is not grounded, the edge capacitance may be artificially increased, thereby increasing the end-effect extension, enabling a physical reduction in patch antenna size.
- Figure 8 shows a transmission line model of the rectangular shorted patch antenna with one edge shorted.
- L 0 is the length of the patch antenna
- Z 0 is the characteristic impedance of the patch antenna
- C is the edge capacitance
- G is the radiation conductance.
- the length L 0 for a half wave rectangular patch antenna is calculated using:
- L 0 is the patch length in meters
- ⁇ o is the wavelength in free space in meters
- ⁇ L is the end effect extension in meters.
- the quarter wave shorted patch antenna is simply half the length of the half wave antenna.
- the end effect extension makes the patch antenna look electrically longer than it actually is. Because of this effect, the physical length of a patch antenna is a little shorter than a quarter wavelength. The electrical length however, is exactly a quarter wavelength at the operating frequency (i.e. resonating frequency).
- the end effect extension ⁇ L is directly related to the amount of capacitance at the capacitive edge 350 and can be represented by the following function:
- ⁇ is the operating frequency in radians/s
- Z 0 is the patch characteristic impedance in ohms.
- Figure 14a shows the reduction in the size of the antenna patch without any capacitance added
- Figure 8b shows that the physical size (length) of the patch can be reduced further by adding capacitance on the edge 360. That is, by adding capacitance to the circuit the physical length (size) of the antenna can be reduced dramatically, while still maintaining the electrical length of a quarter wavelength. Or put another way, the size of a patch antenna operating at a particular resonating frequency can be significantly reduced by adding capacitance.
- Figures 10 to 13 show an alternative embodiment in which both of the opposing edges have capacitors connected. That is Figure 10 shows a perspective view of the patch antenna in which the conduction layer 310' has no edges that are grounded. Instead both edges of the conduction layer 310' with length W have a plurality of capacitors connected. This is not shown in Figure 10, but is shown in Figure 13, in which the edge connected to the feedpoint
- 370' has a first set of capacitors 1300 and the opposite edge having a second set of capacitors 1310.
- both edges of the patch have capacitive edges and this is reflected in Figure 11 , which shows the electromagnetic field radiating from both edges.
- the electromagnetic distribution tapers towards the centre of the patch.
- Figure 12 shows the equivalent transmission line diagram for the embodiment where both edges are capacitive edges.
- any RF point-to- point link system any RF point-to-point link system.
- any RF point-to-multi-point link system any RF point-to-multi-point link system
- any RFID tag whether it is passive or an active tag
- any RF transmitter, receiver and / or transceiver any RF transmitter, receiver and / or transceiver
- the patch antenna according to an embodiment of the present invention was designed in two phases.
- the desired frequency response of the antenna was simulated using electro magnetic simulation software, for example, Sonnet, IE3D, Microware Studio, etc.
- Figure 4 shows a desired frequency response of the antenna using a relevant simulation package. Specifically, Figure 4 shows that the resonating frequency occurs at about 435MHz.
- Figure 5 is a further representation of the same simulation of the small patch antenna according to the preferred embodiment, but whereas Figure 4 showed the frequency response, Figure 5 shows an impedance graph.
- the second phase of antenna design involves prototyping the antenna, which can be constructed for example using ordinary FR-4 PCB material.
- the antenna is then calibrated and a good design rule is that the smaller the patch element, the more capacitance is needed for the antenna to function at the desired resonating frequency.
- a shorted quarter wave patch antenna of a specific size has a resonant frequency of around 2GHz.
- the same size patch antenna, but having the lumped capacitors introduced on its edge is able to operate at a significantly lower resonating frequency, and in this case shown in the plot of Figure 4, reduced by a factor of around 5.
- Figure 4 shows the frequency response of the patch antenna with the lumped capacitors which has a resonating frequency 40 of about 435MHz. It should be appreciated that although the preferred embodiment of Figure 3 provides a substantially rectangular- shaped patch antenna, other shapes are also possible.
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- Waveguide Aerials (AREA)
- Details Of Aerials (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2007255168A AU2007255168A1 (en) | 2006-06-09 | 2007-06-04 | A patch antenna |
BRPI0712363-9A BRPI0712363A2 (en) | 2006-06-09 | 2007-06-04 | antenna for data communication and rectangular laminar antenna |
EP07733068A EP2027627A1 (en) | 2006-06-09 | 2007-06-04 | A patch antenna |
CA002653542A CA2653542A1 (en) | 2006-06-09 | 2007-06-04 | A patch antenna |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0611481.3 | 2006-06-09 | ||
GB0611481A GB0611481D0 (en) | 2006-06-09 | 2006-06-09 | A patch antenna |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2007141505A1 true WO2007141505A1 (en) | 2007-12-13 |
Family
ID=36745640
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB2007/002052 WO2007141505A1 (en) | 2006-06-09 | 2007-06-04 | A patch antenna |
Country Status (7)
Country | Link |
---|---|
EP (1) | EP2027627A1 (en) |
AU (1) | AU2007255168A1 (en) |
BR (1) | BRPI0712363A2 (en) |
CA (1) | CA2653542A1 (en) |
GB (1) | GB0611481D0 (en) |
TW (1) | TW200818606A (en) |
WO (1) | WO2007141505A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8690068B2 (en) | 2012-05-21 | 2014-04-08 | Warsaw Orthopedic, Inc. | Miniaturized UHF RFID tag for implantable medical device |
FR3018361A1 (en) * | 2014-03-10 | 2015-09-11 | Commissariat Energie Atomique | CIRCULAR POLARIZATION RECEIVER-RECEIVER FOR MAGNETIC RESONANCE IMAGING |
US9865926B2 (en) | 2015-09-02 | 2018-01-09 | Qualcomm Incorporated | Low angle radiating shorted half patch antenna |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN114914666B (en) * | 2021-02-10 | 2024-03-26 | 华为技术有限公司 | Antenna and electronic equipment |
CN114122694B (en) * | 2021-11-24 | 2023-05-12 | 西安交通大学 | Roland C receiving antenna based on capacitor |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5767810A (en) * | 1995-04-24 | 1998-06-16 | Ntt Mobile Communications Network Inc. | Microstrip antenna device |
US6509875B1 (en) * | 2001-09-19 | 2003-01-21 | Motorola, Inc. | Electronically tuned active antenna apparatus |
US20040008140A1 (en) * | 2002-04-15 | 2004-01-15 | Sengupta Louise C. | Frequency agile, directive beam patch antennas |
GB2400275A (en) * | 2003-04-01 | 2004-10-06 | Roke Manor Research | Tag transponder mounted on impedance matched antenna |
-
2006
- 2006-06-09 GB GB0611481A patent/GB0611481D0/en not_active Ceased
-
2007
- 2007-06-04 BR BRPI0712363-9A patent/BRPI0712363A2/en not_active Application Discontinuation
- 2007-06-04 CA CA002653542A patent/CA2653542A1/en not_active Abandoned
- 2007-06-04 AU AU2007255168A patent/AU2007255168A1/en not_active Abandoned
- 2007-06-04 EP EP07733068A patent/EP2027627A1/en not_active Withdrawn
- 2007-06-04 WO PCT/GB2007/002052 patent/WO2007141505A1/en active Application Filing
- 2007-06-05 TW TW96120057A patent/TW200818606A/en unknown
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5767810A (en) * | 1995-04-24 | 1998-06-16 | Ntt Mobile Communications Network Inc. | Microstrip antenna device |
US6509875B1 (en) * | 2001-09-19 | 2003-01-21 | Motorola, Inc. | Electronically tuned active antenna apparatus |
US20040008140A1 (en) * | 2002-04-15 | 2004-01-15 | Sengupta Louise C. | Frequency agile, directive beam patch antennas |
GB2400275A (en) * | 2003-04-01 | 2004-10-06 | Roke Manor Research | Tag transponder mounted on impedance matched antenna |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8690068B2 (en) | 2012-05-21 | 2014-04-08 | Warsaw Orthopedic, Inc. | Miniaturized UHF RFID tag for implantable medical device |
FR3018361A1 (en) * | 2014-03-10 | 2015-09-11 | Commissariat Energie Atomique | CIRCULAR POLARIZATION RECEIVER-RECEIVER FOR MAGNETIC RESONANCE IMAGING |
EP2921873A1 (en) | 2014-03-10 | 2015-09-23 | Commissariat A L'energie Atomique Et Aux Energies Alternatives | Transceiver with circular polarisation for magnetic resonance imaging |
US9880241B2 (en) | 2014-03-10 | 2018-01-30 | Commissariat à l'énergie atomique et aux énergies alternatives | Circularly polarized transceiver for magnetic resonance imaging |
US9865926B2 (en) | 2015-09-02 | 2018-01-09 | Qualcomm Incorporated | Low angle radiating shorted half patch antenna |
Also Published As
Publication number | Publication date |
---|---|
BRPI0712363A2 (en) | 2012-06-19 |
CA2653542A1 (en) | 2007-12-13 |
TW200818606A (en) | 2008-04-16 |
GB0611481D0 (en) | 2006-07-19 |
EP2027627A1 (en) | 2009-02-25 |
AU2007255168A1 (en) | 2007-12-13 |
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