Method and apparatus for direction finding using phase comparison

• US 20060082501A1
• Filed: 12/30/2004
• Published: 04/20/2006
• Est. Priority Date: 10/15/2004
• Status: Abandoned Application

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Chiang, Bing A.
• Application Number:
  US11/026,293
• Publication Number:
  US 20060082501A1
• Time in Patent Office: Days
• US Class Current: 342/442
• CPC Class Codes: G01S 3/48 the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured

Abstract

A method and apparatus for direction-finding in elevation using only phase comparison of the received signals are disclosed. The apparatus comprises a vertical linear array, a combiner and a comparator. The vertical antenna array comprises a plurality of antennas and detects signals from a signal source. The combiner combines the detected signals to generate a direction-finding phase signal. The comparator compares the direction-finding phase signal with a phase reference signal derived from a signal received from one of the antennas.

Claims

1. An antenna array for detecting a direction of arrival in elevation, the antenna array comprising:

a vertical linear antenna array comprising a plurality of antennas for detecting signals;

a combiner for combining the signals detected by at least two of the antennas to provide a direction-finding phase signal; and

a comparator for comparing the direction-finding phase signal with a phase reference signal derived from a signal received from one of the antennas, wherein the result of said comparison corresponds to the direction of arrival in elevation.

2. The antenna array of claim 1 wherein the combiner generates a sum mode output by feeding the detected signals in-phase.

3. The antenna array of claim 1 wherein the combiner is a power divider.

4. The antenna array of claim 1 wherein the combiner generates a difference mode output by feeding the detected signals out-of-phase.

5. The antenna array of claim 1 wherein the antenna array comprises two elements which are spaced one-half wavelength apart.

6. The antenna array of claim 1 wherein the phase reference signal is obtained by a directional coupler.

7. The antenna array of claim 1 wherein the linear antenna array comprises three antenna elements and signals detected by two antenna elements are combined to generate the direction-finding phase signal, and a signal detected by the third antenna element is used as the phase reference signal.

8. The antenna array of claim 1 further comprising a phase shifter for shifting a phase of the detected signal, whereby the detected signal is phase shifted before entered into the combiner.

9. The antenna array of claim 8 further comprising a means for steering a beam by feeding back an output of the comparator, whereby the beam is steered in accordance with the output of the comparator.

10. The antenna array of claim 9 wherein the phase shifter is adjusted until the output of the comparator becomes 90 degrees.

11. The antenna array of claim 9 wherein the phase shifter is adjusted until the output of the comparator becomes 180 degrees.

12. A method of detecting a direction of arrival in elevation, the method comprising:

detecting signals with a vertical linear antenna array comprising a plurality of antennas;

combining the signals detected by at least two of the antennas to provide a direction-finding phase signal; and

comparing the phase of the direction-finding phase signal with a phase reference signal derived from a signal received from one of the antennas.

13. The method of claim 12 wherein a sum mode output generated by coupling the detected signals in phase is generated as a direction-finding phase signal.

14. The method of claim 12 wherein the sum mode output is generated by a power divider.

15. The method of claim 12 wherein a difference mode output is generated by coupling the detected signals out-of-phase as a direction-finding phase signal.

16. The method of claim 12 wherein the antenna array comprises two elements which are spaced one-half wavelength apart.

17. The method of claim 12 wherein the phase reference signal is obtained by a directional coupler.

18. The method of claim 12 wherein the linear antenna array comprises three antenna elements and signals detected by two elements are combined to generate the direction-finding phase signal, and a signal detected by the third antenna element is used as the phase reference signal.

19. The method of claim 12 wherein the detected signal is phase shifted before combined to generate a direction-finding phase signal.

20. The method of claim 19 further comprising a step for steering a beam by feeding back an output of the comparator, whereby the beam is steered in accordance with the output of the comparator.

21. The method of claim 20 wherein the phase shifter is adjusted until the output of the comparator becomes 90 degrees.

22. The method of claim 20 wherein the phase shifter is adjusted until the output of the comparator becomes 180 degrees.