GB2396485A - Antenna array with scattering structure - Google Patents
Antenna array with scattering structure Download PDFInfo
- Publication number
- GB2396485A GB2396485A GB0230030A GB0230030A GB2396485A GB 2396485 A GB2396485 A GB 2396485A GB 0230030 A GB0230030 A GB 0230030A GB 0230030 A GB0230030 A GB 0230030A GB 2396485 A GB2396485 A GB 2396485A
- Authority
- GB
- United Kingdom
- Prior art keywords
- transceiver
- antennas
- scattering structure
- scattering
- signals
- Prior art date
- Legal status (The legal status 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 status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
- H04B7/0417—Feedback systems
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
- H01Q19/06—Combinations 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 refracting or diffracting devices, e.g. lens
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q21/00—Antenna arrays or systems
- H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
- H01Q3/44—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
Abstract
A transceiver comprises an antenna array and an associated scattering structure. As shown a diffraction grating 13 is placed in front of a transmission antenna array 12. There may be two or more gratings. A receiver 20 can determine the quality of signal obtained from the antenna array 12 and feed back that information to a controller 14 to modify the grating e.g. by physically adjusting the slot spacing and size. A similar grating can be placed in front of the receiver. The antenna arrangement provides good angular diversity at the receiver in a high capacity Multiple-Input Multiple-Output (MIMO) system and hence good throughput in real world environments such as an office.
Description
Method and Apparatus for Increasing the Number of Strong Egenmodes in a
Multiple-lnput Multiple-Output (MIMO! Radio Channel The present invention relates to communication systems and more particularly to systems utilising the Multiple-lnput Multiple-Output (MIMO) radio channel communication method.
Conventional communication systems have relied upon a single antenna transmitter and single antenna receiver system. However, such systems have a capacity which is fundamentally limited for a given bandwidth and signal-to-noise ratio of the received signal. The use of multiple antennas at the receiver and transmitter (MIMO) extends the system into the spatial domain and fundamentally increases its capacity. A system may then be designed which has a larger potential throughput. A system which has equal numbers of transmit and receive antennas has an inherent capacity which scales approximately linearly with the number of antennas. This is achieved by reuse of the same temporal/spectral channel using independent spatial propagation modes that may be separated at the receiver through signal processing. Consequently such radio systems are becoming increasingly important.
However, the linear relationship between antenna number and fundamental capacity is an over-simplification. In practice, to realise this potential capacity, the receiver has the task of separating the interfering spatial sub-channels. This requires the receiver to determine a sufficient number of independent equations which may be solved to isolate the spatial sub-channels. With current systems, this requires that several unique spatial propagation modes, known as eigenmodes, exist which connect the transmitter and receiver. If the number of strong eigenmodes is lower than the number of transmit (or receive elements) then the potential capacity of the system is reduced.
A channel contains a large number of spatial eigenmodes when there are a large number of rays with a large angular separation that connect the transmitter and the receiver. This
situation occurs when a number of scatterers, i.e. objects causing scattering of the transmitted signal, are located around the antennas. Figure 1 shows how the performance of an uncoded BLAST (Bell Labs Layered Space-Time) architecture, with 6x8 MIMO channel, is degraded (bit error rate (BER) increases) when the angular diversity is small. These results were obtained using a wide sense stationary uncorrelated scattering (WSSUS) channel model. An aim of the present invention is to reduce the performance difference between these two extremes.
Digital beamforming can be used to increase the spatial separation of signals (or to increase the angular acceptance of the receive array). However, this system requires complex digital processing electronics for conditioning the signals prior to feeding to the antenna array for transmission.
With current MIMO systems, there is a danger than the potential throughput may not be achieved in a given environment where sufficiently strong eigenmodes cannot be established to support the multiplexed spatial sub-channels. Consequently, there is a danger that such a system may perform no better or potentially worse than a single antenna system. Thus the considerable investment in a multi-antenna system may not provide any return.
Therefore according to the present invention there is provided a transceiver comprising: an antenna array having a plurality of antennas and a scattering structure associated with the antennas for receiving the signals from the antennas. The invention also provides a transceiver comprising: an antenna array having a plurality of antennas; and a scattering structure associated with the antennas for receiving incoming signals and passing them on to the array of antennas.
The scattering structure scatters the signals from the transmit antenna array to provide good angular diversity at a receiver. Similarly, a scattering structure may be used at the receiver to increase the angular acceptance of the receive array. Potentially this can provide good decorrelation between each of the sub-channels without adversely affecting the power throughput.
The present invention preferably includes a scattering or waveguide structure or structures which may be dynamically adjusted to vary the eigenmodes established between the transmitter and receiver. In this way, the throughput may be improved by varying the scattering in the hope of establishing stronger eigenmodes. Preferably, the transceiver includes a controller for controlling the scattering structure. Ideally, the controller receives information fed back from the receiver to determine whether and how to adjust the scattering structure.
The scattering structure may achieve scattering of the beams from the antennas in any number of ways including, for example, by diffraction, reflection, scattering or refraction, or a combination of them.
In one embodiment, the structure may be formed as a diffraction grating for diffracting the beams. This may be formed from a series of slits formed in a sheet of material, wherein the slits have a different refractive index or absorption coefficient to the spaces between the slits. The slits are preferably adjustable, in their spacing or shape, to provide the adjustment function. Beneficially, two or more diffraction gratings may be used in series to provide further control over the diffraction process. One or more of these may be adjustable.
The present invention also provides a method of scattering signals produced by an array of antennas, the method comprising: interposing a scattering structure between the antennas and a receiver to scatter the beams produced by the antennas, receiving feedback information concerning the strength of the eigenmodes established between the antennas and a receiver; and adjusting the scattering structure to vary the scattering of the beams produced by the antennas.
The present invention relies upon the importance of having diverse paths or eigenmodes between the transmitter and receiver. This is in contrast to traditional single antenna systems where multipath is problematic and so normally avoided.
The present invention provides a system which provides high capacity, by searching out the best propagation modes that exist in any given environment. This is achieved
without the need for complex and expensive circuitry such as that used for digital or analogue beamforming. The present invention instead utilises a simple structure, which is separate from the main antenna thereby providing more degrees of freedom for optimization, to provide an eigenmode rich channel regardless of the local environment.
This will allow a lower cost system with simpler installation since the installer need pay less attention to the radio environment and so the location of the access point.
The arrangement of the present invention also allows for the possibility of three-
dimensional packing of antennas.
The present invention will now be described in more detail with reference to the attached drawings in which: Figure I is a graph showing the affect of angular diversity on the performance of an uncoded BLAST system; and Figure 2 shows a schematic embodiment of a communication system of the present invention. Figure 2 shows schematically an arrangement of an embodiment of the present invention. Although the system is a bidirectional system, the following description will
concentrate only on communication in one direction with the transceiver 10 on the left acting as transmitter and the transceiver 20 on the right acting as receiver. Figure 2 shows a scattering structure 13 arranged adjacent to the array of antennas 12. No scattering structure is shown for the receiver although one could be provided if desired although this is not essential.
In a real-world environment, such as in an office, an access point (AP) is typically located in a convenient location to prevent inconvenience to users. Typically these are mounted on a ceiling. in contrast terminals, particularly mobile terminals, are often located amongst everyday objects of an office. Consequently, the terminals will normally be surrounded by scatterers and the diversity of signals will be sufficient. in contrast, the AP is located away from any scatterers and so signals emanating from it
are unlikely to encounter scatterers in its proximity. In this example, the present invention can be applied to the AP to improve the angular spatial diversity and hence achieve a throughput which is closer to the theoretical maximum channel capacity.
Using this example, the AP is represented by the transmitter 10 and the mobile terminal by the receiver 20.
In use, the transmitter processes the signal to be transmitted and divides this up into the various sub-channels ready for transmission by respective antennas 12. The signals are fed to the antennas 12 of the array to transmit the signal. The scattering structure 13 in this embodiment is a diffraction grating although any structure which causes scattering of the incident signals could be used. The signals impinge on the diffraction grating causing scattering. This scattering can be controlled to couple energy into the strongest spatial eigenmodes supported by the channel.
In figure 2 the diffraction grating is shown as a single structure. The grating may be a single structure or formed from a number of separate gratings. The antenna array 12 may adopt many different geometries, such as linear, planar or circular and the grating may be formed into a structure surrounding the antennas. As indicated above, the grating may consist of a regular periodic structure or it may have a more complex structure to diffract the incident energy in a designed way (e.g. several diffraction orders of nominally equal strength). The scattering structure is shown in figure 2 located in close proximity to the antenna array (but far enough away to be in far-field of the antennas). This is practically convenient
in terns of providing a convenient package. In this way, the structure could be located near the antenna array module in a convenient joint housing.
The transmission diffraction grating of this embodiment, located at the aperture of the receiving antenna module, is used to split the incident beam into several diffraction orders which would have angular diversity. A second grating can be used to further spread the incident beam so that, from the perspective of the receiver antenna elements, the incident beam has emanated from several virtual source points located around the receiver.
Once the transmitted signals from the antennas have passed through the scattering structure, they are received by the antennas 22 at the receiver, e.g. a mobile terminal.
The receiver 20 decodes the received signal to determine the quality of the eigenmodes established between the transmitter and the receiver. The receiver can then transmit the determined quality information back to the transmitter 10. The quality information is extracted and used to adjust the scattering structure. The controller 14 then receives this information and adjusts the scattering structure to modify the grating and thereby vary the eigenmodes developed. For example, the slot spacing and size may be physically modified to bring about a variation in the eigenmodes.
in order to maximise the throughput, the system must establish eigenmodes which have good power efficiency. If weak eigenmodes are established then their poor power transmission will reduce the inherent capacity of that sub-channel. Furthermore, if the terminal moves or objects within the environment move then the transmission paths may change significantly and so dynamic control over the established eigenmodes helps to overcome this. In this way, the signals fed back from the receiver allow the scattering structure to be adjusted to establish strong eigenmodes with high fundamental capacity. By monitoring the received signals and feeding back information from the receiver, the controller 14 can adjust the established modes to maintain high throughput.
As indicated above, a second diffraction grating may be used to further enhance the angular diversity of the signals passing through it. However, this could be taken further and three or more gratings may be used. In order to adjust the eigenmodes developed by the system one or more of such gratings may be adjustable to allow increased flexibility. Furthermore, the scattering structure could be divided up into separate sections, each individually adjustable.
The embodiment described above uses a diffraction grating to increase the angular diversity of the signals passing through it. However, the invention is equally applicable for use with other scattering elements which reflect, refract, diffract or otherwise scatter the incident beam. Furthermore, a combination of devices may be used to perturb the incident radiation.
The above embodiment has been described in respect of transmission primarily in one direction. However, the system is fully capable of operating in reverse with the unit 20 transmitting to the unit 10. The signals impinge on the scattering structure in a similar way albeit form the antennas 22 but the effect is still provided so that the antennas 12 see' the transmitting antennas as spaced apart virtual sources. As indicated, feedback information would be provided to the transceiver with the scattering structure to allow dynamic adjustment. Again, if both transceivers are provided with a scattering structure, then feedback information can be passed in both directions.
The present invention can also be used overcome an interferer. If an interferer is affecting the reception of a sub-channel, the scattering structure can be adjusted to modify the eigenmodes and so avoid using the sub-channel suffering the interference.
In this way the interfering signal can be rejected by the receiver.
The present invention has been described primarily in respect of providing a scattering structure adjacent to the transmitting antenna array. However, the principles of the present invention can be applied where the scattering structure is provided adjacent to the receiving antenna. In this way, rather than providing angular diversity as the signals leave the transmitter structure, the scattering structure effectively defines angularly diverse receive paths for the receiver. This ensures that signals received from the transmitter are angularly diverse, thereby enhancing the capacity of the system.
In this arrangement, the scattering structure can be controlled in a similar way to optimise the eigenmodes between the transmitter and the receiver.
Claims (28)
1. A transceiver comprising: an antenna array having a plurality of antennas; and a scattering structure associated with the antennas for receiving the signals from the antennas.
2. A transceiver according to claim 1, wherein the scattering structure is a passive structure.
3. A transceiver according to claim I or 2, wherein the scattering property of the scattering structure can be externally adjusted.
4. A transceiver according to claim 1, 2 or 3, further comprising a controller for controlling the scattering structure.
5. A transceiver according to claim 4, wherein the controller controls the scattering structure to modify the eigenmodes formed between the transceiver and a receiver.
6. A transceiver according to claim 4 or 5, wherein the controller receives feedback information from the receiver and uses the feedback information for controlling the scattering structure.
7. A transceiver according to any one of claims 1 to 6, wherein the scattering structure scatters the incident signals by at least one of diffraction, reflection or refraction or use of a wave-guide.
8. A transceiver according to any one of claims 1 to 6, wherein the scattering structure is a diffraction grating.
9. A transceiver according to any one of claims 1 to 8, wherein the scattering structure comprises one or more scattering elements, each associated with one or more of said antennas.
10. A transceiver for use with a second transceiver comprising an antenna array having a plurality of antennas and a scattering structure associated with the antennas for receiving the signals from the antennas, the transceiver having an antenna array having a plurality of antennas; feed back means for generating feedback information about the properties of the signals received by the antenna array; and transmission means for sending said feedback information to said second transceiver for adjusting said scattering structure.
11. A transceiver substantially as hereinbefore described with reference to and as shown in the drawings.
12. A communication system comprising a first transceiver and a second transceiver, the second transceiver comprising: a second transceiver antenna array having a plurality of antennas; a scattering structure associated with the antennas for receiving the signals from the antennas; and a controller for controlling the scattering structure, and the first transceiver comprising: a first transceiver antenna array having a plurality of antennas; feed-back means for generating feedback information about the properties of the signals received by the first transceiver antenna array; and transmission means for sending said feedback information to said second transceiver for adjusting said scattering structure.
13. A communication system including a transceiver according to any one or more of claims I to I 1.
14. A method of scattering signals produced by an array of antennas, the method comprising: interposing a scattering structure between the antennas and a receiver to scatter the beams produced by the antennas,
receiving feedback information concerning the strength of the eigenmodes established between the antennas and a receiver; and adjusting the scattering structure to vary the scattering of the beams produced by the antennas.
15. A method according to claim 14, wherein the scattering structure is a passive structure.
16. A method according to claim 14 or 1 5, wherein the scattering structure scatters the incident signals by at least one of diffraction, reflection or refraction.
17. A method according to claim 14 or 15, wherein the scattering structure is a diffraction grating
18. A method according to any one of claims 14 to 17, wherein the scattering structure comprises one or more scattering elements, each associated with one or more of said antennas.
19. A method of scattering signals produced by an array of antennas substantially as hereinbefore described with reference to and as shown in the drawings.
20. A transceiver comprising: an antenna array having a plurality of antennas; and a scattering structure associated with the antennas for receiving incoming signals and passing them on to the array of antennas.
21. A transceiver according to claim 20, wherein the scattering structure is a passive structure.
22. A transceiver according to claim 20 or 21, wherein the scattering property of the scattering structure can be externally adjusted.
23. A transceiver according to claim 20, 21 or 22, further comprising a controller for controlling the scattering structure.
24. A transceiver according to claim 23, wherein the controller controls the scattering structure to modify the eigenmodes formed between the transceiver and a transmitter.
25. A transceiver according to claim 23 or 24, wherein the controller analyses the received signal and uses the information for controlling the scattering structure.
26. A transceiver according to any one of claims 20 to 25, wherein the scattering structure scatters the incident signals by at least one of diffraction, reflection or refraction or use of a wave-guide.
27. A transceiver according to any one of claims 20 to 25, wherein the scattering structure is a diffraction grating.
28. A transceiver according to any one of claims 20 to 27, wherein the scattering structure comprises one or more scattering elements, each associated with one or more of said antennas.
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0230030A GB2396485B (en) | 2002-12-23 | 2002-12-23 | Method and apparatus for increasing the number of strong eigenmodes multiple-input multiple-output (MIMO) radio channel |
| PCT/JP2003/013065 WO2004057702A1 (en) | 2002-12-21 | 2003-10-10 | Method and apparatus for increasing the number of strong eigenmodes in a multiple-input multiple-output (mimo) radio channel |
| CNB038013320A CN100438214C (en) | 2002-12-21 | 2003-10-10 | Method and apparatus for increasing the number of strong eigenmodes in a multiple-input multiple-output (mimo) radio channel |
| JP2004562012A JP4468183B2 (en) | 2002-12-23 | 2003-10-10 | Method and apparatus for increasing the number of strong eigenmodes in a multiple input multiple output (MIMO) radio channel |
| EP03257043.4A EP1434306B1 (en) | 2002-12-23 | 2003-11-07 | Method and apparatus for increasing the number of strong eigenmodes in a mutliple-input multiple output (MIMO) radio channel |
| US10/713,193 US7324786B2 (en) | 2002-12-23 | 2003-11-17 | Method and apparatus for increasing the number of strong eigenmodes in a multiple-input multiple-output (MIMO) radio channel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0230030A GB2396485B (en) | 2002-12-23 | 2002-12-23 | Method and apparatus for increasing the number of strong eigenmodes multiple-input multiple-output (MIMO) radio channel |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB0230030D0 GB0230030D0 (en) | 2003-01-29 |
| GB2396485A true GB2396485A (en) | 2004-06-23 |
| GB2396485B GB2396485B (en) | 2005-03-16 |
Family
ID=9950331
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0230030A Expired - Fee Related GB2396485B (en) | 2002-12-21 | 2002-12-23 | Method and apparatus for increasing the number of strong eigenmodes multiple-input multiple-output (MIMO) radio channel |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US7324786B2 (en) |
| EP (1) | EP1434306B1 (en) |
| JP (1) | JP4468183B2 (en) |
| CN (1) | CN100438214C (en) |
| GB (1) | GB2396485B (en) |
| WO (1) | WO2004057702A1 (en) |
Families Citing this family (23)
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| US7423988B2 (en) | 2005-03-31 | 2008-09-09 | Adc Telecommunications, Inc. | Dynamic reconfiguration of resources through page headers |
| US20060227805A1 (en) * | 2005-03-31 | 2006-10-12 | Adc Telecommunications, Inc. | Buffers handling multiple protocols |
| US7583735B2 (en) | 2005-03-31 | 2009-09-01 | Adc Telecommunications, Inc. | Methods and systems for handling underflow and overflow in a software defined radio |
| US7398106B2 (en) | 2005-03-31 | 2008-07-08 | Adc Telecommunications, Inc. | Dynamic readjustment of power |
| US7640019B2 (en) | 2005-03-31 | 2009-12-29 | Adc Telecommunications, Inc. | Dynamic reallocation of bandwidth and modulation protocols |
| US7593450B2 (en) * | 2005-03-31 | 2009-09-22 | Adc Telecommunications, Inc. | Dynamic frequency hopping |
| US20060223514A1 (en) * | 2005-03-31 | 2006-10-05 | Adc Telecommunications, Inc. | Signal enhancement through diversity |
| EP1722583A1 (en) * | 2005-05-11 | 2006-11-15 | Siemens Aktiengesellschaft | Beam-hopping in a radio communication system |
| US7872981B2 (en) * | 2005-05-12 | 2011-01-18 | Qualcomm Incorporated | Rate selection for eigensteering in a MIMO communication system |
| CN101689901B (en) * | 2007-07-05 | 2012-11-07 | 松下电器产业株式会社 | Radio communication device, radio communication system, radio communication method |
| US10218067B2 (en) | 2015-09-04 | 2019-02-26 | Elwha Llc | Tunable metamaterial systems and methods |
| US10236576B2 (en) | 2015-09-04 | 2019-03-19 | Elwha Llc | Wireless power transfer using tunable metamaterial systems and methods |
| US10447392B2 (en) * | 2016-07-01 | 2019-10-15 | Elwha Llc | Massively multi-user MIMO using space time holography |
| US10374669B2 (en) * | 2016-08-31 | 2019-08-06 | Elwha Llc | Tunable medium linear coder |
| US10928614B2 (en) | 2017-01-11 | 2021-02-23 | Searete Llc | Diffractive concentrator structures |
| US10468776B2 (en) | 2017-05-04 | 2019-11-05 | Elwha Llc | Medical applications using tunable metamaterial systems and methods |
| US10249950B1 (en) | 2017-09-16 | 2019-04-02 | Searete Llc | Systems and methods for reduced control inputs in tunable meta-devices |
| US10425837B2 (en) | 2017-10-02 | 2019-09-24 | The Invention Science Fund I, Llc | Time reversal beamforming techniques with metamaterial antennas |
| US10833381B2 (en) | 2017-11-08 | 2020-11-10 | The Invention Science Fund I Llc | Metamaterial phase shifters |
| CN109412698B (en) * | 2018-10-10 | 2022-01-25 | 南京邮电大学 | Multi-input multi-output optical communication system and communication method based on diffraction effect |
| CN109167612B (en) * | 2018-10-30 | 2019-10-29 | 中国电子科技集团公司第五十四研究所 | One kind defending logical and scatter communication integrated apparatus |
| US10938115B2 (en) | 2019-03-21 | 2021-03-02 | Elwha, Llc | Resonance-frequency diverse metamaterials and metasurfaces |
| CN112563761B (en) * | 2019-09-25 | 2022-07-22 | 上海华为技术有限公司 | Antenna device and signal processing method |
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-
2002
- 2002-12-23 GB GB0230030A patent/GB2396485B/en not_active Expired - Fee Related
-
2003
- 2003-10-10 CN CNB038013320A patent/CN100438214C/en not_active Expired - Fee Related
- 2003-10-10 WO PCT/JP2003/013065 patent/WO2004057702A1/en active Application Filing
- 2003-10-10 JP JP2004562012A patent/JP4468183B2/en not_active Expired - Fee Related
- 2003-11-07 EP EP03257043.4A patent/EP1434306B1/en not_active Expired - Lifetime
- 2003-11-17 US US10/713,193 patent/US7324786B2/en not_active Expired - Fee Related
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3553702A (en) * | 1968-08-07 | 1971-01-05 | Itt | Waveguide radiator with perpendicular scattering posts at aperture |
| US4119951A (en) * | 1977-02-16 | 1978-10-10 | Gilles Garon | Microwave intrusion sensing units and antenna therefor |
| DE4313395A1 (en) * | 1993-04-23 | 1994-11-10 | Hirschmann Richard Gmbh Co | Planar antenna |
| US6459414B1 (en) * | 2000-07-03 | 2002-10-01 | Her Majesty The Queen In Right Of Canada As Represented By The Minister Of Industry | Dual-polarized and circular-polarized antennas |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0230030D0 (en) | 2003-01-29 |
| JP4468183B2 (en) | 2010-05-26 |
| CN1572046A (en) | 2005-01-26 |
| EP1434306A1 (en) | 2004-06-30 |
| GB2396485B (en) | 2005-03-16 |
| US7324786B2 (en) | 2008-01-29 |
| CN100438214C (en) | 2008-11-26 |
| JP2006512000A (en) | 2006-04-06 |
| WO2004057702A1 (en) | 2004-07-08 |
| US20040162034A1 (en) | 2004-08-19 |
| EP1434306B1 (en) | 2017-10-04 |
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