USH2033H1 - Method and means for providing enhanced main beam nulling in antijamming antenna - Google Patents
Method and means for providing enhanced main beam nulling in antijamming antenna Download PDFInfo
- Publication number
- USH2033H1 USH2033H1 US06/606,742 US60674284A USH2033H US H2033 H1 USH2033 H1 US H2033H1 US 60674284 A US60674284 A US 60674284A US H2033 H USH2033 H US H2033H
- Authority
- US
- United States
- Prior art keywords
- antenna
- gain
- signal
- sum
- azimuth
- 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.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims description 15
- 238000004891 communication Methods 0.000 claims abstract description 10
- 230000001965 increasing effect Effects 0.000 claims description 8
- 230000002708 enhancing effect Effects 0.000 claims description 6
- 238000012545 processing Methods 0.000 claims description 2
- 238000001514 detection method Methods 0.000 abstract description 2
- 230000003044 adaptive effect Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000013459 approach Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007123 defense Effects 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005562 fading Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/28—Details of pulse systems
- G01S7/2813—Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
- G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
- G01S3/14—Systems for determining direction or deviation from predetermined direction
- G01S3/28—Systems for determining direction or deviation from predetermined direction using amplitude comparison of signals derived simultaneously from receiving antennas or antenna systems having differently-oriented directivity characteristics
- G01S3/32—Systems for determining direction or deviation from predetermined direction using amplitude comparison of signals derived simultaneously from receiving antennas or antenna systems having differently-oriented directivity characteristics derived from different combinations of signals from separate antennas, e.g. comparing sum with difference
Definitions
- This invention relates to antijamming antenna techniques for reducing the vulnerability of line of sight and troposcatter microwave communications links to jamming.
- the invention comprehends an antenna with an improved gain control circuit for enhancing the null performance of the antenna against a jammer close to antenna boresight.
- Antijamming antenna techniques have been developed which reduce vulnerability of line of sight and troposcatter microwave communications links to jamming.
- the techniques are incorporated in an antenna system that is configured to adaptively place a null in the direction of a jammer with an arrival angle close to the direction of arrival of a decreased signal (within the main beam) as well as a jammer arriving in the sidelobe region of the main antenna. Spatial discrmination prevents nulling of the desired signal in the absence of jamming an improved signal/jamming ratio for jamming levels comparable to the desired signal level.
- the antenna system utilized includes an auxiliary antenna that consists of a dual plane, multimode, monopulse feed which replaces the standard feed, a low gain slot array and an omnidirectional antenna.
- the method of the present invention of increasing null performance for jammers close to the desired signal DOA is to increase the gain of the monopulse antenna auxiliary difference beams.
- This can be accomplished spatially or by electronic means.
- the aperture size and spatial gain available is already fixed and only electronic gain is available.
- the penalty for using electronic gain is an increase in the System Noise floor.
- a particular characteristic of line of sight microwave communication links of the type to which the invention pertains is that they are designated to have large fade margins and therefore the received signal at one of the diversity antennas is usually strong and well above the noise floor.
- Advantage of this can be taken by the AJ antenna by increasing the electronic gain in the monopulse antenna auxiliary difference beam channels in a controlled manner. This permits nulling a jammer closer to boresight of the antenna. The resulting increase in noise does not degrade system performance in cases where the signal is well above noise floor at one of the diversity antennas.
- the invention comprises an antenna system with an improved gain control circuit for enhancing null; performance of the antenna against a jammer close to antenna boresight.
- the antenna system is provided with an auxiliary monopulse system having sum azimuth difference and elevation difference ports.
- An adaptive system senses the auxiliary port outputs in conjunction with the signal/noise ratio of the antenna processor output and increases the gain in the difference circuits in response to certain conditions that indicate the presence of a dominant jammer.
- a dominant jammer is indicated when the power level in the sum port exceeds the power levels of both difference ports and the signal/noise ratio of the processor output is unsatisfactory.
- FIG. 1 is a block diagram showing the enhanced main beam processor configuration of the invention
- FIG. 2 is a performance curve of S/(J+N) vs angle of jammer off boresight with 0 electronic gain
- FIG. 3 is a performance curve of S/(J+N) vs angle of jammer off boresight with 3dB electronic gain
- FIG. 4 is a performance curve of S/(J+N) vs angle of jammer off boresight with 6dB electronic gain
- FIG. 5 is a performance curve of S/(J+N) vs angle of jammer off boresight with 9dB electronic gain
- FIG. 6 is a simplified block diagram of the enhanced main beam null configuration of the invention.
- the invention provides enhanced main beam nulling in the antenna system of a line of sight or troposcatter microwave communications link. It comprises a method and means for improving null performance for jammers close to the desired signal direction of arrival.
- FIG. 1 A block diagram of an antenna configuration of the type to which the invention may be applied is shown in FIG. 1 . It comprises a monopulse system that includes complex feed 10 , antenna combiner 13 , auxiliary receivers 14 , 15 , main receiver 16 , horn (or main) antenna 11 , omnidirectional antenna 12 , auxiliary receivers 26 , 27 , adaptive weights 20 - 23 and processor 24 . Variable gains 18 , 19 in the azimuth and elevation difference channel of the monopulse system provide additional gain in accordance with the principles of the invention.
- a controlled amount of gain is introduced into the difference ports of the monpulse system by means of variable gains 18 and/or 19 .
- an interference signal can be nulled that is much closer in angle to the desired signal than would be the case when the gain is the same in both channels.
- FIGS. 2-5 The basic principle of the invention is illustrated in FIGS. 2-5. For these cases a J/N of +60 dB and JIN of +20 dB were used. In developing the curves of: FIGS. 2-5 the desired signal was centered on the peak of the beam while the jammer was moved in azimuth from the beam peak to five degrees away from the peak. The S/J+N ratio is plotted with and without the AJ antenna processor.
- FIG. 2 demonstrates the procedure with no electronic gain in the main auxiliary path.
- FIG. 3 shows the effect of adding 3 dB of electronic gain in the A AZ auxiliary port.
- the adapted response in the vicinity of peak has sharpened considerably, that is the jammer can be closer to the direction of arrival (DOA) of the signal and be nulled.
- the tesult of increasing the gain from 3 dB to 6 dB is shown in FIG. 4 . Additional sharpening of the adapted response is noted.
- Increasing the gain still further to 9 dB (FIG. 5) produces little additional sharpening and begins to affect the sdidelobe region.
- FIG. 6 is a simplified block diagram of the enhanced main beam null configuration.
- this configuration includes an angle discriminant 30 , a signal/noise measurement device 32 and gain control logic 31 . These are conventional radar system components and perform their required functions in the normal way.
- the monopulse feed is an ideal direction of arrival indicator. That is the jammer's arrival angle with respect to antenna boresight can be determined accurately for relatively small J/S ratios.
- a simple but effective approach to apply the enhanced nulling techniques adaptively, senses the power in the sum port (non-processed) and Az/EL difference ports. If the power in the sum port exceeds the power sensed in both difference ports, it indicates that a signal is in the angular cone around boresight when the normal processor is not effective. The question is whether this is the desired signal alone or is a dominant jammer also present. This is determined by the performance monitoring circuit. If satisfactory S/N is indicated for SIN measure 32 , the processor 24 remains in its normal configuration.
- S/N is unsatisfactory, it indicates a jammer is within the sector where normal processing is ineffective.
- These measurements are monitored by a gain control logic circuit 31 which selects the additional gain for enhanced mainbeam null performance as may be required.
- the gain control logic also provides stabilization control to prevent constant gain switching for pulsed or fading conditions.
Abstract
In a microwave communications link, an antijamming antenna system with enhanced main beam nulling is realized by providing gain in the difference port output of a monopulse antenna compared to the sum port. As a consequence interference signals are nulled out at much closer angles to the desired signal than is the case when the gain is the same in both channels. The gain is introduced when a dominant jammer is detected. Detection of a dominant jammer is identified for the conditions in which the monopulse sum channel power level exceeds the sum of the difference channel power levels and the system processor output signal/noise ratio is unsatisfactory.
Description
The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.
This invention relates to antijamming antenna techniques for reducing the vulnerability of line of sight and troposcatter microwave communications links to jamming.
Specifically, the invention comprehends an antenna with an improved gain control circuit for enhancing the null performance of the antenna against a jammer close to antenna boresight.
It has been demonstrated that in existing Defense communications systems there exists the need to protect all directions of arrival of a desired signal against jamming; jamming effectiveness is greatest in the main beam and near-in sidelobe regions of the antenna. Computed jamming/signal ratios for various simulated encounters has showed that an integrated adaptive main beam-sidelobe canceller antenna is required to significantly reduce communication outages due to the various jamming encounters.
Antijamming antenna techniques have been developed which reduce vulnerability of line of sight and troposcatter microwave communications links to jamming. The techniques are incorporated in an antenna system that is configured to adaptively place a null in the direction of a jammer with an arrival angle close to the direction of arrival of a decreased signal (within the main beam) as well as a jammer arriving in the sidelobe region of the main antenna. Spatial discrmination prevents nulling of the desired signal in the absence of jamming an improved signal/jamming ratio for jamming levels comparable to the desired signal level. The antenna system utilized includes an auxiliary antenna that consists of a dual plane, multimode, monopulse feed which replaces the standard feed, a low gain slot array and an omnidirectional antenna.
One problem encountered in the system developed was that of the inability to effectively null jammers that are close to the direction of arrival of the desired signal. In this regard it has been determined, and it is fundamental to the present invention that nulling jammers close to the direction of arrival of the desired signal than is indicated by existing techniques can be achieved at the expense of signal/noise ratio. This represents a trade off that is beneficial for some scenarios.
The method of the present invention of increasing null performance for jammers close to the desired signal DOA is to increase the gain of the monopulse antenna auxiliary difference beams. This can be accomplished spatially or by electronic means. For a specific reflector antenna the aperture size and spatial gain available is already fixed and only electronic gain is available. As indicated above, the penalty for using electronic gain is an increase in the System Noise floor. A particular characteristic of line of sight microwave communication links of the type to which the invention pertains is that they are designated to have large fade margins and therefore the received signal at one of the diversity antennas is usually strong and well above the noise floor. Advantage of this can be taken by the AJ antenna by increasing the electronic gain in the monopulse antenna auxiliary difference beam channels in a controlled manner. This permits nulling a jammer closer to boresight of the antenna. The resulting increase in noise does not degrade system performance in cases where the signal is well above noise floor at one of the diversity antennas.
The invention comprises an antenna system with an improved gain control circuit for enhancing null; performance of the antenna against a jammer close to antenna boresight. The antenna system is provided with an auxiliary monopulse system having sum azimuth difference and elevation difference ports. An adaptive system senses the auxiliary port outputs in conjunction with the signal/noise ratio of the antenna processor output and increases the gain in the difference circuits in response to certain conditions that indicate the presence of a dominant jammer. A dominant jammer is indicated when the power level in the sum port exceeds the power levels of both difference ports and the signal/noise ratio of the processor output is unsatisfactory.
It is a principal object of the invention to provide a new and improved method for effecting main beam nulling in antijamming antennas.
It is another object of the invention to provide an improved method of nulling out interference signals at angles close to boresight in antijamming antennas.
It is another object of the invention to provide, in an antijamming antenna, means for nulling jammers closer to the direction of arrival of desired signals than has heretofore been possible.
It is another object of the invention to provide an antijamming antenna system having adaptive means for detecting the presence of and nulling out jammers close to boresight.
These together with other features and advantages of the invention will become more readily apparent from the following detailed description when taken in conjunction with the illustrative embodiment in the accompanying drawings.
FIG. 1 is a block diagram showing the enhanced main beam processor configuration of the invention;
FIG. 2 is a performance curve of S/(J+N) vs angle of jammer off boresight with 0 electronic gain;
FIG. 3 is a performance curve of S/(J+N) vs angle of jammer off boresight with 3dB electronic gain;
FIG. 4 is a performance curve of S/(J+N) vs angle of jammer off boresight with 6dB electronic gain;
FIG. 5 is a performance curve of S/(J+N) vs angle of jammer off boresight with 9dB electronic gain; and
FIG. 6 is a simplified block diagram of the enhanced main beam null configuration of the invention.
The invention provides enhanced main beam nulling in the antenna system of a line of sight or troposcatter microwave communications link. It comprises a method and means for improving null performance for jammers close to the desired signal direction of arrival.
A block diagram of an antenna configuration of the type to which the invention may be applied is shown in FIG. 1. It comprises a monopulse system that includes complex feed 10, antenna combiner 13, auxiliary receivers 14, 15, main receiver 16, horn (or main) antenna 11, omnidirectional antenna 12, auxiliary receivers 26, 27, adaptive weights 20-23 and processor 24. Variable gains 18, 19 in the azimuth and elevation difference channel of the monopulse system provide additional gain in accordance with the principles of the invention.
In practicing the invention a controlled amount of gain is introduced into the difference ports of the monpulse system by means of variable gains 18 and/or 19. As a result an interference signal can be nulled that is much closer in angle to the desired signal than would be the case when the gain is the same in both channels.
The basic principle of the invention is illustrated in FIGS. 2-5. For these cases a J/N of +60 dB and JIN of +20 dB were used. In developing the curves of: FIGS. 2-5 the desired signal was centered on the peak of the beam while the jammer was moved in azimuth from the beam peak to five degrees away from the peak. The S/J+N ratio is plotted with and without the AJ antenna processor.
FIG. 2 demonstrates the procedure with no electronic gain in the main auxiliary path. FIG. 3 shows the effect of adding 3 dB of electronic gain in the A AZ auxiliary port. The adapted response in the vicinity of peak has sharpened considerably, that is the jammer can be closer to the direction of arrival (DOA) of the signal and be nulled. The tesult of increasing the gain from 3 dB to 6 dB is shown in FIG. 4. Additional sharpening of the adapted response is noted. Increasing the gain still further to 9 dB (FIG. 5) produces little additional sharpening and begins to affect the sdidelobe region. There are several problems in applying this approach to the system. For example, if a fixed amount of gain were inserted in the difference beam auxiliaries, the effectiveness of the spatial discriminant would be reduced and a loss in S/N would occur for scenarios where the sharpended response is not required. These problems can be alleviated by making use of the jammer detection and performance monitoring ciruits shown in FIG. 6.
FIG. 6 is a simplified block diagram of the enhanced main beam null configuration. In addition to the antenna elements common to those shown in FIG. 1 this configuration includes an angle discriminant 30, a signal/noise measurement device 32 and gain control logic 31. These are conventional radar system components and perform their required functions in the normal way.
The monopulse feed is an ideal direction of arrival indicator. That is the jammer's arrival angle with respect to antenna boresight can be determined accurately for relatively small J/S ratios. A simple but effective approach, to apply the enhanced nulling techniques adaptively, senses the power in the sum port (non-processed) and Az/EL difference ports. If the power in the sum port exceeds the power sensed in both difference ports, it indicates that a signal is in the angular cone around boresight when the normal processor is not effective. The question is whether this is the desired signal alone or is a dominant jammer also present. This is determined by the performance monitoring circuit. If satisfactory S/N is indicated for SIN measure 32, the processor 24 remains in its normal configuration. If S/N is unsatisfactory, it indicates a jammer is within the sector where normal processing is ineffective. These measurements are monitored by a gain control logic circuit 31 which selects the additional gain for enhanced mainbeam null performance as may be required. The gain control logic also provides stabilization control to prevent constant gain switching for pulsed or fading conditions.
While the invention has been described in one presently preferred embodiment it is understood that the words which have been used are words of description rather than words of limitation and that changes within the purview of the appended claims may be made without departing from the scope and spirit of the invention in its broader aspects.
Claims (7)
1. In an antijamming antenna system having a main antenna, an omnidirectional antenna, a monopulse antenna with azimuth and elevation difference beam ports each having gain and a sum beam port, and a processor receiving signals therefrom and providing a processed output, the method of enhancing main beam nulling comprising the step of
increasing gain in said difference beam ports.
2. In an antijamming antenna system having a main antenna, an omnidirectional antenna, a monopulse antenna with azimuth and elevation difference beam ports each having gain and a sum beam port, and a processor receiving signals therefrom and providing a processed output, the method of enhancing main beam nulling comprising the steps of
detecting the presence of a dominant jamming signal from the power levels in said monopulse antenna sum and difference beam ports and the signal/noise ratio of said processed output, and
increasing gain in said difference beam ports in response thereto.
3. In an antijamming antenna system having a main antenna, an omnidirectional antenna, a monopulse antenna with azimuth and elevation difference beam ports each having gain and a sum beam port, and a processor receiving signals therefrom and providing a processed output, the method of enhancing main beam nulling defined in claim 2 wherein the presence of a dominant jamming signal is detected by the steps of
sensing the power level in said monopulse antenna sum beam port,
sensing the power levels in said monopulse antenna difference beam ports,
determining if the signal/noise ratio of said processed output is satisfactory or unsatisfactory, and
identifying the presence of a dominant jamming signal for the condition that the power in the sum beam port exceeds the power in both difference beam ports and the signal/noise ratio of said processed output is unsatisfactory.
4. In an antijamming antenna system having a main antenna, an omnidirectional antenna, a monopulse antenna with azimuth and elevation difference beam ports each having gain and a sum beam port, and a processor receiving signal therefrom and providing a processed output, the method of enhancing main beam nulling defined in claim 3 wherein gain in said difference beam ports is increased by an amount in a range between 3dB and 9dB.
5. In a microwave communications link, an aritijamming antenna system comprising
a main antenna,
an omnidirectional antenna,
a monopulse antenna outputting azimuth and elevation difference signals and sum signals,
processor means receiving and processing the outputs of said main antennas, said omnidirectional antenna and said monopulse antenna azimuth and elevation difference signals and sum signals, and providing a processed output therefrom,
jamming signal detecting means for detecting and outputting a signal in response to the presence of a dominant jamming signal, said jamming signal detecting means detecting jamming signals from the power levels of said monopulse antenna azimuth and elevation difference signals and sum signals and the signal/noise ratio of said processed output, and
gain control means for increasing the gain of said moncpulse antenna azimuth and elevation difference signals in response to the jamming signal detecting means output signal.
6. In a microwave communications link, an antijamming antenna as defined in claim 5 wherein said gain control means increases the gain of said monopulse antenna azimuth and elevation difference signals in response to the conditions in which the power level of said sum signal is greater than the total power of said azimuth and elevation difference signals and the signal/noise ratio of said processed output is less than a preselected threshold.
7. In a microwave communications link, an antijamming antenna as defined in claim 6 wherein said gain control means increases the gain of said monopulse azimuth and elevation difference signals by an amount in a range between 3dB and 9dB.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/606,742 USH2033H1 (en) | 1984-03-01 | 1984-03-01 | Method and means for providing enhanced main beam nulling in antijamming antenna |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/606,742 USH2033H1 (en) | 1984-03-01 | 1984-03-01 | Method and means for providing enhanced main beam nulling in antijamming antenna |
Publications (1)
Publication Number | Publication Date |
---|---|
USH2033H1 true USH2033H1 (en) | 2002-07-02 |
Family
ID=24429268
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US06/606,742 Abandoned USH2033H1 (en) | 1984-03-01 | 1984-03-01 | Method and means for providing enhanced main beam nulling in antijamming antenna |
Country Status (1)
Country | Link |
---|---|
US (1) | USH2033H1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20020105462A1 (en) * | 2000-03-14 | 2002-08-08 | Hans Bloecher | Device and method for an antenna array with switchable wide-angle coverage |
US20040005858A1 (en) * | 2002-07-03 | 2004-01-08 | Alexandre Cervinka | Detector of commercial jammer |
US20080068266A1 (en) * | 2005-11-23 | 2008-03-20 | Northrop Grumman Corporation | Beamforming for spatial sidelobe cancellation and AMR direction finding |
US20100178952A1 (en) * | 2003-08-20 | 2010-07-15 | Qualcomm Incorporated | Method and apparatus for uplink rate selection in the presence of multiple transport channels in a wireless communication system |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3766559A (en) | 1971-10-20 | 1973-10-16 | Harris Intertype Corp | Adaptive processor for an rf antenna |
US4023172A (en) | 1959-12-17 | 1977-05-10 | Numax Electronics Incorporated | Monopulse system for cancellation of side lobe effects |
US4097866A (en) | 1977-02-10 | 1978-06-27 | The United States Of America As Represented By The Secretary Of The Air Force | Multilevel sidelobe canceller |
US4170775A (en) | 1977-12-30 | 1979-10-09 | The United States Of America As Represented By The Secretary Of The Air Force | Communication system beamport sidelobe canceller |
US4177464A (en) | 1978-11-13 | 1979-12-04 | The United States Of America As Represented By The Secretary Of The Air Force | Multiplexing of multiple loop sidelobe cancellers |
US4316190A (en) * | 1979-06-05 | 1982-02-16 | The Marconi Company Limited | Secondary surveillance radar |
US4516126A (en) * | 1982-09-30 | 1985-05-07 | Hazeltine Corporation | Adaptive array having an auxiliary channel notched pattern in the steered beam direction |
-
1984
- 1984-03-01 US US06/606,742 patent/USH2033H1/en not_active Abandoned
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4023172A (en) | 1959-12-17 | 1977-05-10 | Numax Electronics Incorporated | Monopulse system for cancellation of side lobe effects |
US3766559A (en) | 1971-10-20 | 1973-10-16 | Harris Intertype Corp | Adaptive processor for an rf antenna |
US4097866A (en) | 1977-02-10 | 1978-06-27 | The United States Of America As Represented By The Secretary Of The Air Force | Multilevel sidelobe canceller |
US4170775A (en) | 1977-12-30 | 1979-10-09 | The United States Of America As Represented By The Secretary Of The Air Force | Communication system beamport sidelobe canceller |
US4177464A (en) | 1978-11-13 | 1979-12-04 | The United States Of America As Represented By The Secretary Of The Air Force | Multiplexing of multiple loop sidelobe cancellers |
US4316190A (en) * | 1979-06-05 | 1982-02-16 | The Marconi Company Limited | Secondary surveillance radar |
US4516126A (en) * | 1982-09-30 | 1985-05-07 | Hazeltine Corporation | Adaptive array having an auxiliary channel notched pattern in the steered beam direction |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20020105462A1 (en) * | 2000-03-14 | 2002-08-08 | Hans Bloecher | Device and method for an antenna array with switchable wide-angle coverage |
US6954176B2 (en) * | 2000-03-14 | 2005-10-11 | Daimlerchrysler Ag | Device and method for an antenna array with switchable wide-angle coverage |
US20040005858A1 (en) * | 2002-07-03 | 2004-01-08 | Alexandre Cervinka | Detector of commercial jammer |
US20100178952A1 (en) * | 2003-08-20 | 2010-07-15 | Qualcomm Incorporated | Method and apparatus for uplink rate selection in the presence of multiple transport channels in a wireless communication system |
US8463309B2 (en) * | 2003-08-20 | 2013-06-11 | Qualcomm Incorporated | Method and apparatus for uplink rate selection in the presence of multiple transport channels in a wireless communication system |
US8472994B2 (en) | 2003-08-20 | 2013-06-25 | Qualcomm Incorporated | Method and apparatus for uplink rate selection in the presence of multiple transport channels in a wireless communication system |
US20080068266A1 (en) * | 2005-11-23 | 2008-03-20 | Northrop Grumman Corporation | Beamforming for spatial sidelobe cancellation and AMR direction finding |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US5739788A (en) | Adaptive receiving antenna for beam repositioning | |
US7145503B2 (en) | Surface wave radar | |
EP1159635B1 (en) | Radar system having spoofer, blanker and canceler | |
US5371506A (en) | Simultaneous multibeam approach for cancelling multiple mainlobe jammers while preserving monopulse angle estimation accuracy on mainlobe targets | |
Farina et al. | Electronic counter-countermeasures | |
EP1167995B1 (en) | Matrix monopulse ratio radar processor for two target azimuth and elevation angle determination | |
EP0913706B1 (en) | IFF systems | |
US5440308A (en) | Apparatus and method for employing adaptive interference cancellation over a wide bandwidth | |
US5361074A (en) | Mainlobe canceller system | |
JPH10501891A (en) | Radar equipment | |
USH2033H1 (en) | Method and means for providing enhanced main beam nulling in antijamming antenna | |
US4367472A (en) | Circuit arrangement for side lobe suppression in radar apparatuses | |
US6653969B1 (en) | Dispersive jammer cancellation | |
US4472719A (en) | ECM Multiple-target retrodirective antenna | |
CN112269165A (en) | Interference method and system acting on self-adaptive side lobe cancellation system | |
NO317455B1 (en) | Antenna system, especially for beam width regulation | |
Brookner | Cognitive adaptive array processing (Caap)-Adaptivity made easy | |
Brookner | Cognitive adaptive array processing (CAAP)—Its time has come | |
US4646094A (en) | Method of discriminating between signals | |
Sedehi et al. | Impact of an electromagnetic interference on imaging capability of a synthetic aperture radar | |
US4370655A (en) | Combined side lobe canceller and frequency selective limiter | |
US6236364B1 (en) | Method and arrangement for improving null depths | |
Arkoumaneas | Effectiveness of a ground jammer | |
Brookner | MIMO versus conventional radar performance against jammers | |
Arisesa et al. | The effect of external interference on the performance of navigation radar |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: UNITED STATES OF AMERICA AS REPRESENTED BY THE SEC Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. SUBJECT TO LICENSE RECITED.;ASSIGNORS:HAZELTINE CORPORATION;MASAK, RAYMOND J.;LACKEY, RAYMOND J.;REEL/FRAME:004307/0555;SIGNING DATES FROM 19840131 TO 19840202 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |