System and method to form coherent wavefronts for arbitrarily distributed phased arrays

• US 8,681,047 B2
• Filed: 10/27/2010
• Issued: 03/25/2014
• Est. Priority Date: 11/04/2009
• Status: Expired due to Fees

• 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: Egri, Robert G., Winter, Christopher C.
• Primary Examiner(s): LIU, HARRY K
• Application Number:
  US12/913,558
• Publication Number:
  US 20110102261A1
• Time in Patent Office: 1,245 Days
• Field of Search: 342/368, 342371-372
• US Class Current: 342/368
• 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 configured to transmit waves at different frequencies to the array of nodes 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 with respect to a desired focal point, wherein the signals transmitted from the plurality of transceivers are constructively combined at an arbitrary direction in point and space independent of locations of the plurality of beacons.

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 wherein the plurality of beacons comprise a plurality of primary beacons and 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 such that the frequencies are different based on a location thereof.

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 periodically transmit a coherent wavefront in the direction of the plurality of beacons, wherein the coherent wavefront is created by referencing an arbitrary target location relative to the array of nodes, transmitting a calibration signal from the plurality of beacons to the plurality of nodes, receiving the calibration signal at the plurality of nodes, calculating a wavefront curvature correction, and transmitting a complex amplitude signal from the array nodes as the coherent wavefront.

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 one or more beacons of 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 of a reference coordinate system for the frequencies of the plurality of beacons to point to 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 scanning pattern.

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

18. 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 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.

19. A system in accordance with claim 18 wherein the plurality of beacons comprise three beacons configured to be used to measure an array phase distribution as a function of direction.