SYSTEM AND METHOD TO FORM COHERENT WAVEFRONTS FOR ARBITRARILY DISTRIBUTED PHASED ARRAYS

• US 20110102261A1
• Filed: 10/27/2010
• Published: 05/05/2011
• Est. Priority Date: 11/04/2009
• Status: Active Grant

• Current Assignee: Cobham Defense Electronic Systems-M/A-Com Incorporated (Cobham PLC)
• Original Assignee: Cobham Defense Electronic Systems-M/A-Com Incorporated (Cobham PLC)
• Inventors: Winter, Christopher C., Egri, Robert G.
• Granted Patent: US 8,681,047 B2
• Time in Patent Office: Days
• US Class Current: 342/371
• CPC Class Codes: H01Q 1/241 used in mobile communications, e.g. GSM H01Q1/247, H01Q1/248 take precedence
• CPC Class Codes: H01Q 1/28 Adaptation for use in or on aircraft, missiles, satellites, or balloons
• CPC Class Codes: H01Q 1/288 Satellite antennas
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching

Abstract

A system and method for providing coherent sources for phased arrays are provided. One method includes providing a plurality of transceivers configured to transmit signals and defining an array of nodes. The method also includes providing a plurality of beacons at different frequencies to one of aim or focus phase coherent energy generated by the transmitted signals from the plurality of transceivers, wherein the phase coherent energy is transmitted at a direction and a frequency determined with phase conjugation and independent of the location of the plurality of beacons.

Claims

1. A method of array focusing, the method comprising:

providing a plurality of transceivers configured to transmit signals and defining an array of nodes; and

providing a plurality of beacons at different frequencies to one of aim or focus phase coherent energy generated from the plurality of transceivers of the array, the phase coherent energy transmitted at a direction and at a frequency that are controlled by the transmit frequencies of the plurality of beacons that are located arbitrarily.

2. A method in accordance with claim 1 wherein to focus a beam anywhere in a plane spanned by two beacons and an arbitrary coplanar reference point.

3. A method in accordance with claim 1 wherein the beacons comprise at least three beacons and arbitrary non-coplanar reference point to focus the beam in any direction of space to operate for three-dimensional scanning.

4. A method in accordance with claim 1 further comprising configuring the beacons to operate as test receivers to determine coherence of the array.

5. A method in accordance with claim 1 further comprising providing a plurality of secondary beacons configured as fixed emitters operating at a fixed and different frequency than the plurality of beacons, and wherein a plurality of additional primary beacons are configured to provide adjustable location dependent frequencies.

6. A method in accordance with claim 1 wherein the plurality of transceivers include antennas with corresponding accelerometers coupled thereto, and further comprising configuring the transceivers to use the sensed motion to reset direct phase measurements between the plurality of transceivers.

7. A method in accordance with claim 1 further comprising randomly locating the plurality of transceivers.

8. A method in accordance with claim 1 further comprising configuring the plurality of transceivers for frequency locking and phase locking therebetween.

9. A method in accordance with claim 1 further comprising configuring the array of nodes formed from the plurality of transceivers to transmit a coherent wavefront in the direction of the plurality of beacons periodically.

10. A method in accordance with claim 1 further comprising providing an oscillator clock associated with one of the transceivers to lock corresponding clocks associated with the other transceivers, and providing a global positioning system (GPS) device for initial position estimation.

11. A method in accordance with claim 1 further comprising decomposing desired transmit phases of the nodes into linear combinations of received phases from the plurality of beacons.

12. A method in accordance with claim 1 further comprising configuring the plurality of beacons as single frequency references.

13. A method in accordance with claim 1 further comprising configuring the plurality of beacons as multi-frequency references.

14. A method in accordance with claim 1 further comprising at least four beacons and further comprising decomposing a direction vector of a target into more than three affine components.

15. A method in accordance with claim 1 further comprising shifting an origin for a reference coordinate system for the frequencies of the plurality of beacons.

16. A method in accordance with claim 1 further comprising configuring the plurality of transceivers to scan a focus of the phase coherent energy using a discrete raster.

17. A method in accordance with claim 1 further comprising configuring the plurality of transceivers to operate in pulse mode.

18. A method for forming a coherent wavefront for array focusing, the method comprising:

decomposing a target direction {right arrow over (R)}_t⁰ vector in an affine coordinate system spanned by beacon vectors {right arrow over (b)}₁⁰,{right arrow over (b)}₂⁰,{right arrow over (b)}₃⁰ as ⁰{right arrow over (R)}_t=c₁{right arrow over (b)}₁⁰+c₂{right arrow over (b)}₂⁰+c₃{right arrow over (b)}₃⁰;

transmitting a calibration signal from a beacon j at a wave-number κ

_j=κ

|c_j| to a plurality of nodes;

receiving a beacon signal at node n and measuring a phasor p_nj=e<sup>−

lκ

j|{right arrow over (a)}n−

{right arrow over (b)}j|</sup>;

calculating a wavefront curvature correction e<sup>lθ

n0</sup>; and

transmitting a complex amplitude signal E_n=e<sup>lθ

n0</sup>s_n1s_n2s_n3,

where

19. A system for array focusing, the system comprising:

at least one radio having a plurality of transceivers configured to transmit signals, the plurality of transceivers defining an array of nodes; and

a plurality of beacons configured to operate at different frequencies to one of aim or focus phase coherent energy generated by the transmitted signals from the plurality of transceivers, wherein the phase coherent energy is transmitted at a direction and a frequency determined with phase conjugation and independent of the location of the plurality of beacons.

20. A system in accordance with claim 19 wherein the plurality of beacons comprise three beacons configured to measure an array phase distribution as a function of direction.