Scalable, analog monopulse network

• US 9,124,361 B2
• Filed: 10/06/2011
• Issued: 09/01/2015
• Est. Priority Date: 10/06/2011
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Puzella, Angelo M., Tsai, Tunglin L., Bozza, Donald A., Scott, Kathe I., Dupuis, Patricia S., Francis, John B.
• Primary Examiner(s): Sotomayor, John B
• Assistant Examiner(s): WINDRICH, MARCUS E
• Application Number:
  US13/267,193
• Publication Number:
  US 20130088381A1
• Time in Patent Office: 1,426 Days
• Field of Search: 342/80, 342/149, 342/154, 342/372
• US Class Current: 1/1
• CPC Class Codes: G01S 13/4463 using phased arrays
• CPC Class Codes: G01S 7/032 Constructional details for solid-state radar subsystems
• CPC Class Codes: H01Q 21/0025 Modular arrays
• CPC Class Codes: H01Q 21/0093 Monolithic arrays
• CPC Class Codes: H01Q 25/02 providing sum and difference patterns H01Q25/04 takes precedence
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements

Abstract

Embodiments of the concepts described herein are directed toward a common RF building block in the form of a monolithic assembly for an AESA array featuring a scalable RF design based on 2ⁿ:3 combining. The monopulse network building blocks are substantially identical, enabling an interchangeable sub-array architecture that is independent of position in the AESA aperture and receive sum channel sidelobe performance. In one embodiment, a passive Monopulse Beamformer may provide the passive 2ⁿ:3 RF coupling/combining network and an active Monopulse Processor may perform amplitude and phase weighting for the combined signals from the Monopulse Beamformer.

Claims

1. A phased array having an aperture, the phased array comprising:

multiple sub-arrays, each of the multiple sub-arrays comprising;

a plurality of antenna elements;

a beamformer having a plurality of beamformer antenna ports operably coupled to the sub-array antenna elements, said beamformer configured to passively combine signals from the sub-array antenna elements, in a 2ⁿ;

3 ratio wherein n is an integer corresponding to the number of beamformer antenna ports wherein said beamformer comprises;

a plurality of elevation signal couplers disposed between the beamformer antenna ports and a delta elevation signal port, said elevation signal couplers having one of a plurality of elevation coupling values;

a plurality of azimuth signal couplers disposed between the beamformer antenna ports and a delta azimuth signal port, said azimuth signal couplers having one of a plurality of azimuth coupling values; and

a plurality of transmit/sum signal couplers disposed between the beamformer antenna ports and a sum signal port, said sum signal couplers having one of a plurality of transmit/sum coupling values; and

wherein said beamformer forms monopulse signals at the sum signal port, the delta azimuth signal port, and the delta elevation signal port with the monopulse signals corresponding to;

a sum signal, a delta azimuth signal, and a delta elevation signal for the sub-array and wherein;

the elevation coupling values of said analog monopulse beamformer are substantially identical in each of the multiple sub-arrays regardless of the physical position of said sub-array within the phased array;

the azimuth coupling values of said beamformer are substantially identical in each of the multiple sub-arrays regardless of the physical position of said sub-array within the phased array;

the transmit/sum coupling values of said beamformer are substantially identical in each of the multiple sub-arrays regardless of the position of said sub-array within the phased array; and

a monopulse processor having a sum signal port, a delta azimuth signal port and a delta elevation signal port operably connected to respective ones of the sum, delta azimuth and delta elevation signal ports of said beamformer, said monopulse processor configured to receive monopulse signals from said beamformer and apply a weight level to each of the monopulse signals independently of one another to form corresponding weighted monopulse signals for the first sub-array;

wherein the weight levels are selected based upon the physical location of the sub-array within the aperture of the phased array.

2. The phased array of claim 1 further comprising a plurality of transmit/receive modules coupled between said plurality of antenna elements and said beamformer.

3. The phased array of claim 1, wherein said monopulse processor further comprises at least one weighting circuit configured to condition at least one monopulse signal provided from thereto from said beamformer.

4. The phased array of claim 1, wherein said monopulse processor is configured to provide controllable weight values to the monopulse signals, the controllable weight values assigned based upon the position of the sub-array within the phased array.

10. The phased array of claim 1 wherein:

said beamformer in each of said sub-array modules is provided as a passive analog monopulse beamformer; and

said monopulse processor in each of said sub-array modules is provided as an active monopulse processor.

5. A method for monopulse beamforming in a phased array having an aperture and comprised of a plurality of subarray modules, each subarray module comprising a plurality of antenna elements, an analog beamformer and a monopulse processor, the method comprising:

receiving return signals from a target at each of the plurality of sub-array modules in the phased array;

at each subarray, coupling the return signal to the subarray beamformer and passively combining the return signals with a first set of elevation coupling values to form a delta elevation monopulse signal;

at each subarray, coupling the return signal to the subarray beamformer and passively combining the return signals with a first set of azimuth coupling values to form a delta azimuth monopulse signal;

at each subarray, coupling the return signal to the subarray beamformer and passively combining the return signals with a first set of sum coupling values to form a sum monopulse signals;

providing the delta elevation, delta azimuth and sum monopulse signals to the monopulse processor associated with the sub-array;

conditioning, in the monopulse processor each of the delta elevation, delta azimuth and sum monopulse signals independently of one another to form corresponding weighted monopulse signals for the first sub-array wherein said conditioning depends upon a physical position of the sub-array within the aperture of the phased array; and

tracking said target using said weighted monopulse signals.

6. The method of claim 5, wherein said receiving said return signals further comprises conditioning the return signal from at least one of said antenna elements of the first sub-array prior to passively combining.

7. The method of claim 5, wherein said receiving said monopulse signals in said monopulse processor further comprises conditioning at least one of said monopulse signals using an active electronic component.

8. The method of claim 5, wherein said conditioning in the monopulse processor using an active electronic component comprises applying a weight to the delta elevation and delta azimuth monopulse signals using a weighting circuit.

9. The method of claim 5, wherein said conditioning in the monopulse processor comprises applying controllable weight values to the delta elevation and delta azimuth monopulse signals, the controllable weight values selected based upon the physical position of the sub-array within the aperture of the phased array.

11. A phased array having an aperture, the phased array comprising:

a plurality of sub-array modules, each sub-array module comprising;

a sub-array of antenna elements;

a beamformer having a plurality of beamformer antenna ports coupled to the sub-array antenna elements, said beamformer comprising;

a plurality of elevation signal couplers coupled between the beamformer antenna ports and a delta elevation signal port of said beamformer, said plurality of elevation signal couplers having elevation coupling values wherein the elevation coupling values are identical in each of the plurality of sub-array modules regardless of the position of said sub-array module within the phased array aperture;

a plurality of azimuth signal couplers coupled between the beamformer antenna ports and an azimuth elevation signal port of said beamformer, said plurality of azimuth signal couplers having azimuth coupling values wherein the azimuth coupling values are substantially identical in each of the plurality of sub-array modules regardless of the position of said sub-array module within the phased array aperture; and

a plurality of transmit/sum signal couplers coupled between the beamformer antenna ports and a sum signal port of said beamformer, said plurality of transmit/sum signal couplers having transmit/sum coupling values wherein the transmit/sum coupling values are substantially identical in each of said plurality of sub-array modules regardless of the position of said sub-array module within the phased array aperture; and

wherein in response to signals provided thereto from said sub-array antenna elements, said beamformer forms sum, delta azimuth and delta elevation monopulse signals for the sub-array module at respective ones of the sum, the delta azimuth, and the delta elevation signal ports of said beamformer; and

an active monopulse processor having a sum signal port, a delta azimuth signal port and a delta elevation signal port coupled to respective ones of the sum, delta azimuth and delta elevation signal ports of said beamformer, said active monopulse processor configured to receive monopulse signals from said beamformer and apply a weight level to each of the monopulse signals independently of one another to form corresponding weighted monopulse signals for the sub-array module at corresponding ones of a sum output port, a delta azimuth output port and a delta elevation output port wherein the weight levels are selected based upon the physical location of the sub-array module within the phased array aperture.

12. The phased array of claim 11 wherein said plurality of elevation signal couplers are provided having a selected set of elevation coupling values and said plurality of azimuth signal couplers are provided having a selected set of azimuth coupling values and the elevation coupling values in the selected set of elevation coupling values match the azimuth coupling values in the selected set of azimuth coupling values.

13. The phased array of claim 11 wherein said plurality of elevation signal couplers are provided having a selected set of elevation coupling values and said plurality of azimuth signal couplers are provided having a selected set of azimuth coupling values and the elevation coupling values in the selected set of elevation coupling values differ from the azimuth coupling values in the selected set of azimuth coupling values.

14. The phased array of claim 11 wherein said active monopulse processor comprises:

a sum signal processing branch having a first end coupled to the sum signal port and a second end coupled to a sum output port;

at least one of;

a delta azimuth signal processing branch having a first end coupled to the delta azimuth signal port and a second end coupled to the delta azimuth output port; and

a delta elevation signal processing branch having a first end coupled to the delta elevation signal port and a second end coupled to the delta elevation output port.

15. The phased array of claim 14 wherein:

said sum signal processing branch comprises at least one signal divider having an input coupled to the sum signal port, having a first output coupled to the sum output port and having a second output coupled to at least one of said delta azimuth signal processing branch and delta elevation signal processing branch;

said delta azimuth signal processing branch comprises;

a signal combiner having an output coupled to the delta azimuth output port and having first and second inputs;

an amplifier having an input coupled to the delta azimuth signal port and an output coupled to the first input of said signal combiner;

a weighting circuit having an input coupled to the second output of said signal divider and having an output coupled to the second input of said signal combiner; and

said delta elevation signal processing branch comprises;

a signal combiner having an output coupled to the delta elevation output port and having first and second inputs;

an amplifier having an input coupled to the delta elevation signal port and an output coupled to the first input of said signal combiner;

a weighting circuit having an input coupled to the second output of said signal divider and having an output coupled to the second input of said signal combiner.

16. An active electronically steered phased array (AESA) having an aperture, the AESA comprising:

a plurality of AESA sub-array modules, each of the sub-array modules comprising;

a sub-array of antenna elements;

a passive, analog monopulse beamformer having a plurality of beamformer antenna ports coupled to the sub-array of antenna elements, said passive, analog monopulse beamformer configured to passively combine signals from the sub-array of antenna elements to form monopulse signals, said passive, analog monopulse beamformer comprising;

a plurality of elevation signal couplers disposed between the beamformer antenna ports and a delta elevation signal port, said elevation signal couplers having elevation coupling values;

a plurality of azimuth signal couplers disposed between the beamformer antenna ports and a delta azimuth signal port, said azimuth signal couplers having azimuth coupling values; and

a plurality of transmit/sum signal couplers disposed between the beamformer antenna ports and a sum signal port, said sum signal couplers having transmit/sum coupling values; and

wherein said passive, analog monopulse beamformer forms monopulse signals at the sum signal port, the delta azimuth signal port, and the delta elevation signal port with the monopulse signals corresponding to;

a sum signal, a delta azimuth signal, and a delta elevation signal for the sub-array and wherein;

the elevation coupling values of said passive, analog monopulse beamformer are substantially identical in each AESA sub-array module regardless of the position of said AESA sub-array module within the AESA;

the azimuth coupling values of said passive, analog monopulse beamformer are substantially identical in each AESA sub-array module regardless of the position of said AESA sub-array module within the AESA;

the transmit/sum coupling values of said passive, analog monopulse beamformer are substantially identical in each AESA sub-array module regardless of the position of said AESA sub-array module within the AESA; and

an active monopulse processor having a sum signal port, a delta azimuth signal port and a delta elevation signal port coupled to respective ones of the sum, delta azimuth and delta elevation signal ports of said passive, analog monopulse beamformer, said active monopulse processor configured to receive monopulse signals from said passive analog monopulse beamformer and apply a weight level to each of the monopulse signals independently of one another to form corresponding weighted monopulse signals for the AESA sub-array module wherein the weight levels are selected based upon the physical location of the AESA sub-array module within the overall aperture of the AESA.

17. The phased array of claim 16 wherein said plurality of elevation signal couplers are provided having a selected set of elevation coupling values and said plurality of azimuth signal couplers are provided having a selected set of azimuth coupling values and the elevation coupling values in the selected set of elevation coupling values match the azimuth coupling values in the selected set of azimuth coupling values.

18. The phased array of claim 16 wherein said plurality of elevation signal couplers are provided having a selected set of elevation coupling values and said plurality of azimuth signal couplers are provided having a selected set of azimuth coupling values and the elevation coupling values in the selected set of elevation coupling values differ from the azimuth coupling values in the selected set of azimuth coupling values.

19. The phased array of claim 16 wherein said active monopulse processor comprises:

a sum signal processing branch having a first end coupled to the sum signal port and a second end coupled to a sum output port;

at least one of;

a delta azimuth signal processing branch having a first end coupled to the delta azimuth signal port and a second end coupled to the delta azimuth output port; and

a delta elevation signal processing branch having a first end coupled to the delta elevation signal port and a second end coupled to the delta elevation output port.

20. The phased array of claim 19 wherein:

said sum signal processing branch comprises at least one signal divider having an input coupled to the sum signal port, having a first output coupled to the sum output port and having a second output coupled to at least one of said delta azimuth signal processing branch and delta elevation signal processing branch;

said delta azimuth signal processing branch comprises;

a signal combiner having an output coupled to the delta azimuth output port and having first and second inputs;

an amplifier having an input coupled to the delta azimuth signal port and an output coupled to the first input of said signal combiner;

a weighting circuit having an input coupled to the second output of said signal divider and having an output coupled to the second input of said signal combiner; and

said delta elevation signal processing branch comprises;

a signal combiner having an output coupled to the delta elevation output port and having first and second inputs;

an amplifier having an input coupled to the delta elevation signal port and an output coupled to the first input of said signal combiner;

a weighting circuit having an input coupled to the second output of said signal divider and having an output coupled to the second input of said signal combiner.