Method and apparatus for detecting, locating, and identifying microwave transmitters and receivers at distant locations

• US 20060109159A1
• Filed: 11/22/2004
• Published: 05/25/2006
• Est. Priority Date: 11/22/2004
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Holly, Sandor
• Granted Patent: US 7,142,147 B2
• Time in Patent Office: Days
• US Class Current: 342/13
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/46 Indirect determination of position data
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: G01S 7/021 Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals
• CPC Class Codes: G01V 8/005 operating with millimetre waves, e.g. measuring the black losey radiation

Abstract

Methods and apparatuses for detecting, locating, and identifying microwave transmitters and receivers at distant locations are disclosed. First and second electromagnetic beams at first and second frequencies, respectively, are transmitted in first and second directions. The second frequency is offset from the first frequency to define an interference difference frequency. As such, the first and second electromagnetic beams interfere at a far field distance corresponding to an intersection of the first and second electromagnetic beams. In the far field the beams interfere with microwave devices that reradiate a return radiation at the difference frequency. The methods and apparatuses detect the return radiation at the difference frequency, such as by way of a receiver, and locate the interference zone to determine the location of the microwave device, such as by a processor.

Claims

1. A method of detecting, locating, and identifying at least one of microwave transmitters or microwave receivers at a distant location, comprising:

transmitting a first electromagnetic beam at a first frequency and in a first direction;

transmitting a second electromagnetic beam at a second frequency and in a second direction, wherein the second frequency is offset from the first frequency to define an interference difference frequency, and the first and second electromagnetic beams interfere at a far field distance corresponding to an intersection of the first and second electromagnetic beams;

detecting a return radiation at the difference frequency produced by interference with a microwave device in the intersection,

locating the interference zone to determine the location of the microwave device; and

identifying the microwave device according to the return radiation at the difference frequency.

2. The method according to claim 1, wherein the step of locating comprises locating the interference zone azimuthally based upon the direction of at least one of the first or second directions.

3. The method according to claim 1, wherein the step of locating comprises locating the interference zone based upon triangulation of the first and second directions.

4. The method according to claim 1, wherein the step of identifying the microwave device comprises determining a cut-off frequency from the return radiation at the difference frequency.

5. The method according to claim 4, further comprising comparing the cut-off frequency with cut-off frequencies of microwave devices to determine the type of microwave device.

6. The method according to claim 1, wherein the step of identifying the microwave device comprises spectrally analyzing the return radiation at the difference frequency.

7. The method according to claim 6, further comprising comparing the spectral analysis to characteristics of other microwave devices to determine the type of microwave device.

8. The method according to claim 1, wherein the steps of transmitting the first and second electromagnetic beams further comprises collimating the first electromagnetic beam in a first direction and collimating the second electromagnetic beam in the second direction.

9. The method according to claim 1, wherein the steps of transmitting the first and second electromagnetic beams comprises further comprises combining the first and second beams in a third direction, and collimating the first and second beams in the third direction.

10. The method according to claim 9, wherein the step of combining the first and second electromagnetic beams comprises combining linearly polarized first and second beams through a polarization beam combiner.

11. The method according to claim 9, wherein the step of combining the first and second electromagnetic beams comprises combining circularly polarized first and second beams through a circular polarization beam combiner.

12. The method according to claim 1, wherein the step of transmitting further comprises scanning the first and second electromagnetic beams.

13. A method of detecting, locating, and identifying at least one of microwave transmitters or microwave receivers at a distant location, comprising:

transmitting at least two electromagnetic beams separated by at least one interference difference frequency;

collimating the at least two electromagnetic beams such that the collimated at least two electromagnetic beams interfere at a far field distance;

detecting a return radiation at the difference frequency produced by interference with a microwave device in the far field distance;

locating an interference zone to determine the location of the microwave device; and

identifying the microwave device according to the return radiation at the difference frequency.

14. The method according to claim 13, wherein the step of locating comprises locating the interference zone azimuthally based upon the direction of at least one of the first or second directions.

15. The method according to claim 13, wherein the step of locating comprises locating the interference zone based upon triangulation of the first and second directions.

16. The method according to claim 13, wherein the step of identifying the microwave device comprises comparing return radiation at the difference frequency to characteristics of microwave devices.

17. The method according to claim 13, wherein the step of identifying the microwave device comprises spectrally analyzing the return radiation at the difference frequency and comparing the spectral analysis to characteristics of microwave devices.

18. The method according to claim 13, further comprising combining the at least two electromagnetic beams.

19. The method according to claim 13, further comprising scanning the at least two electromagnetic beams.

20. An apparatus for detecting, locating, and identifying at least one of microwave transmitters or microwave receivers at a distant location, comprising:

a first transmitter configured to transmit a first electromagnetic beam at a first frequency and in a first direction;

a second transmitter configured to transmit a second electromagnetic beam at a second frequency and in a second direction, wherein the second frequency is offset from the first frequency to define an interference difference frequency, and the first and second transmitters are configured such that the first and second beams interfere with a microwave device at a far field distance corresponding to an intersection of the first and second directions;

a receiver configured to receive a return radiation at the difference frequency generated from the interference with the microwave device;

a processor interconnected to the receiver and configured to identify the microwave device according to the return signal.

21. The apparatus according to claim 20, further comprising a scanner for scanning the first and second beams through an area to detect the microwave device.

22. The apparatus according to claim 20, wherein the scanner comprises a scan mirror capable of reflecting first and second electromagnetic beams.

23. The apparatus according to claim 20, further comprising a beam combiner for combining the first and second electromagnetic beams.

24. The apparatus according to claim 20, further comprising a collimator for collimating the combined first and second electromagnetic beams in a third direction.

25. The apparatus according to claim 20, further comprising a first collimator for collimating the first electromagnetic beam in the first direction, and a second collimator for collimating the second electromagnetic beam in the second direction.