Multi-beam antenna with interference cancellation network

• US 6,642,883 B2
• Filed: 08/30/2001
• Issued: 11/04/2003
• Est. Priority Date: 08/30/2001
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Jacomb-Hood, Anthony Wykeham, Lier, Erik, Volman, Vladimir
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US09/942,444
• Publication Number:
  US 20030052819A1
• Time in Patent Office: 796 Days
• Field of Search: 342/354, 342/352, 342/379, 455/13.3
• US Class Current: 342/354
• CPC Class Codes: H01Q 25/00 Antennas or antenna systems providing at least two radiating patterns arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00
• CPC Class Codes: H01Q 3/2611 Means for null steering; Adaptive interference nulling

Abstract

A means and method to increase the beam traffic capacity, especially in high user density regions, of a multi-beam antenna communication system with multiple signals at any frequency transmitted (received) when in a transmit (receive) mode by canceling interference with neighboring signals. An interference cancellation network is provided for canceling the interference caused by the sidelobe(s) of at least one signal with one or more of the other signals in the network. Each power divider divides its input signal into one reference fractional signal and at least one non-reference fractional signal. Phase shifters/attenuators shift the phase and attenuate the amplitude of at least one of the non-reference fractional signals. Each power combiner combines its input reference fractional signal with at least one non-reference fractional signal into a composite signal emerging from the combiner. The phase/attenuation settings are selected to optimize the signal to interference ratio for each communications link.

Claims

1. A system for increasing the beam traffic capacity of a multi-beam antenna system, the multi-beam antenna system capable of being used in a transmit mode, the system having a plurality of signals at any frequency transmitted when the multi-beam antenna is used as a transmit antenna,

the system comprising:

said multi-beam antenna, and

a separate, dedicated interference cancellation means for canceling interference with at least one signal, the interference being caused by at least one antenna beam sidelobe, the interference cancellation means being connected to the multi-beam antenna, wherein

when the multi-beam antenna system is used in a transmit mode,

at least one of the plurality of beams transmitted by the multi-beam antenna is pointed towards at least one remote user,

said interference cancellation means having an input port for each of the plurality of signals,

said interference cancellation means creating a plurality of composite signals, said interference cancellation means having an output port for each of the composite signals,

the transmit antenna having an input port connected to each output port of said interference cancellation means such that the composite signals become the input signals to the transmit multi-beam antenna, and the composite signals emerging from said interference cancellation means optimize the signal to interference ratio at the at least one remote user;

said interference cancellation means being a network in the multi-beam antenna system comprising a plurality of power dividers and a plurality of power combiners,

each power divider having an input port connected to the transmit signal intended to be transmitted by the transmit multi-beam antenna,

each of said power dividers dividing the signal connected to said input port into one reference fractional signal and at least one non-reference fractional signal, therein defining said power divider as a source power divider to said one reference fractional signal and to said at least one non-reference fractional signal, said source power divider having a plurality of output ports,

an output port of said source power divider containing said reference fractional signal being connected to an input port of one of said power combiners, therein defining said power combiner as a companion power combiner to said source power divider,

each output port of said source power divider containing a non-reference fractional signal being connected to an input port of another one of said power combiners, therein defining said another one of said power combiners as an associated power combiner to said source power divider,

each companion power combiner receiving at least one non-reference fractional signal through a path connecting from the source power divider of said at least one non-reference fractional signal, therein defining said source power divider of said at least one non-reference fractional signal as an associated power divider to said companion power combiner,

each of said companion power combiners combining said reference fractional signal emerging from said companion source power divider with said at least one non-reference fractional signal from an associated power divider into a composite output signal,

wherein an output port of each of said power combiners is connected to an input port of the transmit multi-beam antenna such that said composite signals emerging from said interference cancellation means at said output ports of each of said power combiners become the signals transmitted at any frequency when the multi-beam antenna is used as a transmit antenna.

2. The system of claim 1 wherein the multi-beam antenna is an active phased array antenna.

3. The system of claim 1 wherein the multi-beam antenna is a reflector class antenna with multiple feeds.

4. The system of claim 1 wherein said dividing means comprises a reciprocal combining means.

5. The system of claim 1 wherein said combining means comprises a reciprocal dividing means.

6. The system of claim 1 wherein attenuating means are included for attenuating the amplitude of at least one of said non-reference fractional signals to achieve the desired amplitude relative to at least one of said reference fractional signals.

7. The system of claim 6 wherein said attenuating means is included with one of said (a) combining means, and (b) dividing means.

8. The system of claim 1 wherein phase shifting means are included for shifting the phase of at least one of said plurality of non-reference fractional signals to achieve the desired phase relative to at least one of said reference fractional signals.

9. The system of claim 8 wherein said phase shifting means is included with one of said (a) combining means, and (b) dividing means.

10. The system of claim 1 wherein attenuating means are included for attenuating the amplitude of said reference fractional signal.

11. The system of claim 10 wherein said attenuating means is included with one of said (a) combining means, and (b) dividing means.

12. The system of claim 1 wherein phase shifting means are included for shifting the phase of said reference fractional signal.

13. The system of claim 12 wherein said phase shifting means is included with one of said (a) combining means, and (b) dividing means.

28. The system of claim 1 wherein said system is a system for increasing the beam traffic capacity in a region around any remote user, the size of the region being on the order of 3 to 5 beam widths in any direction from the remote user.

14. A system for increasing the beam traffic capacity of a multi-beam antenna system, the multi-beam antenna system capable of being used in a receive mode, the system having a plurality of signals at any frequency received when the multi-beam antenna is used as a receive antenna,

the system comprising:

said multi-beam antenna, and

a separate, dedicated interference cancellation means for canceling interference with at least one signal, the interference being caused by at least one antenna beam sidelobe, the interference cancellation means being connected to the multi-beam antenna, wherein

when the multi-beam antenna system is used in a receive mode,

each beam of the receive antenna collects a signal, referred to as the intended signal, from at least one remote user,

the sidelobe of at least one beam collecting at least one signal from at least one other remote user, the signal from the at least one other remote user causing interference to the intended signal in the beam,

the receive antenna having for each beam an output port which is connected to an input port of said interference cancellation means such that both the intended signal and the interference emerging from each output port of the receive multi-beam antenna are injected into said interference cancellation means at said input port,

said interference cancellation means creating a plurality of composite signals,

said interference cancellation means having an output port for each of the composite signals,

the composite signals emerging from said output port of said interference cancellation means optimize the signal to interference ratio of at least one intended signal collected from the at least one remote user,

said interference cancellation means being a network in said multi-beam antenna system comprising a plurality of power dividers and a plurality of power combiners,

each power divider having an input port connected to an output port of the receive multi-beam antenna, such that the signals at any frequency received when the multi-beam antenna is used as a receive antenna become the input signals to said interference cancellation network,

each of said power dividers dividing the signal connected to said input port into one reference fractional signal and at least one non-reference fractional signal, therein defining said power divider as a source power divider to said one reference fractional signal and to said at least one non-reference fractional signal, said source power divider having a plurality of output ports,

an output port of said source power divider containing the reference fractional signal being connected to an input port of one of said power combiners, therein defining said power combiner as a companion power combiner to said source power divider,

each output port of said source power divider containing a non-reference fractional signal being connected to an input port of another one of said power combiners, therein defining said another one of said power combiners as an associated power combiner to said source power divider, each companion power combiner receiving at least one non-reference fractional signal through a path connecting from the source power divider of said at least one non-reference fractional signal, therein defining said source power divider of said at least one non-reference fractional signal as an associated power divider to said companion power combiner,

wherein each of said companion power combiners combines said reference fractional signal emerging from said companion source power divider with said at least one non-reference fractional signal from an associated power divider into a composite output signal, said composite output signal emerging from an output port of each power combiner of said interference cancellation network,

each said output port of each of said power combiners of said interference cancellation network being an output port of said receive multi-beam antenna system, such that said composite output signal of said interference cancellation network is an output signal of the receive multi-beam antenna system.

15. The system of claim 14 wherein said dividing means comprises a reciprocal combining means.

16. The system of claim 14 wherein said combining means comprises a reciprocal dividing means.

17. The system of claim 14 wherein attenuating means are included for attenuating the amplitude of at least one of said non-reference fractional signals to achieve the desired amplitude relative to at least one of said reference fractional signals.

18. The system of claim 17 wherein said attenuating means is included with one of said (a) combining means, and (b) dividing means.

19. The system of claim 14 wherein phase shifting means are included for shifting the phase of at least one of said plurality of non-reference fractional signals to achieve the desired phase relative to at least one of said reference fractional signals.

20. The system of claim 19 wherein said phase shifting means is included with one of said (a) combining means, and (b) dividing means.

21. The system of claim 14 wherein attenuating means are included for attenuating the amplitude of said reference fractional signal.

22. The system of claim 21 wherein said attenuating means is included with one of said (a) combining means, and (b) dividing means.

23. The system of claim 14 wherein phase shifting means are included for shifting the phase of said reference fractional signal.

24. The system of claim 23 wherein said phase shifting means is included with one of said (a) combining means, and (b) dividing means.

25. The system of claim 14 wherein said system is a system for increasing the beam traffic capacity in a region around any remote user, the size of the region being on the order of 3 to 5 beam widths in any direction from the remote user.

26. The system of claim 14 wherein the multi-beam antenna is an active phased array antenna.

27. The system of claim 14 wherein the multi-beam antenna is a reflector class antenna with multiple feeds.

29. A method for increasing the beam traffic capacity of a multi-beam antenna transmitting a plurality of beams operating at any frequency,

at least one of said plurality of beams pointed toward a remote user,

at least one other of said plurality of beams having at least one sidelobe directed towards the remote user causing interference at the remote user with the signal contained in the beam pointed toward the remote user,

said method performed by means of a separate, dedicated interference cancellation network having as input a plurality of transmit signals each intended to correspond to one of the plurality of beams operating at any frequency,

said interference cancellation network comprising a plurality of dividers and a plurality of combiners,

each of said plurality of dividers having a companion combiner and at least one associated combiner,

each of said plurality of combiners having a companion divider and at least one associated divider,

each of said dividers having an input port for one of the plurality of transmit signals, said method comprising the steps of:

(a) applying each of the plurality of transmit signals to the input ports of each of said dividers,

(b) dividing in each of said dividers each of the transmit signals into a reference fractional signal and at least one non-reference fractional signal,

said reference fractional signal and said non-reference fractional signal therein each having a common source divider,

(c) transporting said reference fractional signal to said companion combiner of said common source divider,

(d) transporting said at least one non-reference fractional signal to one of said at least one associated combiners of said common source divider, and

(e) combining in each of said companion combiners said one reference fractional signal from said companion divider with said at least one non-reference fractional signal from said at least one associated divider into a composite signal,

said composite signal thereby optimizing the signal to interference ratio at the remote user.

30. The method of claim 29, following step (b) of dividing in each of said dividers each of said transmit signals into a reference fractional signal and at least one non-reference fractional signal, further comprising the step of

attenuating the amplitude of said at least one of said plurality of non-reference fractional signals to achieve the desired amplitude relative to at least one of said reference fractional signals.

31. The method of claim 29, following step (b) of dividing in each of said dividers each of said transmit signals into a reference fractional signal and at least one non-reference fractional signal, further comprising the step of

shifting the phase of said at least one of said plurality of non-reference fractional signals to achieve the desired phase relative to the phase of at least one of said reference fractional signals.

32. The method of claim 29 wherein the multi-beam antenna is an active phased array antenna.

33. The method of claim 29 wherein the multi-beam antenna is a reflector class antenna with multiple feeds.

34. The method of claim 29 wherein said method is a method for increasing the beam traffic capacity in a region around any remote user, the size of the region being on the order of 3 to 5 beam widths in any direction from the remote user.

35. A method for increasing the beam traffic capacity of a multi-beam antenna receiving a plurality of beams operating at any frequency, the multi-beam antenna having a receive signal output port for each of the plurality of beams operating at any frequency,

at least one of the plurality of beams collecting an intended signal from at least one remote user,

the at least one of the plurality of beams having at least one sidelobe collecting at least one signal from at least one other remote user,

the at least one signal from the at least one other remote user acting as interference to the intended signal emerging from the output port of the multi-beam receive antenna associated with the at least one beam collecting an intended signal from at least one remote user,

said method performed by means of a separate, dedicated interference cancellation network having as input a plurality of receive signals emerging from the output ports of the receive multi-beam antenna,

said interference cancellation network comprising a plurality of dividers and a plurality of combiners,

each of said plurality of dividers having a companion combiner and at least one associated combiner,

each of said plurality of combiners having a companion divider and at least one associated divider,

each of said dividers having an input port for one of the output receive signals corresponding to one of the plurality of beams received by the multi-beam antenna,

said method comprising the steps of:

(a) applying each of the receive signals emerging from the output ports of the receive multi-beam antenna to the input ports of each of said dividers,

(b) dividing in each of said dividers each of the receive signals into a reference fractional signal and at least one non-reference fractional signal,

said reference fractional signal and said non-reference fractional signal therein each having a common source divider,

(c) transporting said reference fractional signal to said companion combiner of said common source divider,

(d) transporting said at least one non-reference fractional signal to one of said at least one associated combiners of said common source divider, and

(e) combining in each of said companion combiners said one reference fractional signal from said companion divider with said at least one non-reference fractional signal from said at least one associated divider into a composite signal,

said composite signal thereby optimizing the signal to interference ratio of said intended signal collected from said at least one remote user.

36. The method of claim 35, following step (b) of dividing in each of said dividers each of said receive signals into a reference fractional signal and at least one non-reference fractional signal, further comprising the step of

attenuating the amplitude of said at least one of said plurality of non-reference fractional signals to achieve the desired amplitude relative to at least one of said reference fractional signals.

37. The method of claim 35, following step (b) of dividing in each of said dividers each of said receive signals into a reference fractional signal and at least one non-reference fractional signal, further comprising the step of

shifting the phase of said at least one of said plurality of non-reference fractional signals to achieve the desired phase relative to the phase of at least one of said reference fractional signals.

38. The method of claim 35 wherein the multi-beam antenna is an active phased array antenna.

39. The method of claim 35 wherein the multi-beam antenna is a reflector class antenna with multiple feeds.

40. The method of claim 35 wherein said method is a method for increasing the beam traffic capacity in a region around any remote user, the size of the region being on the order of 3 to 5 beam widths in any direction from the remote user.