Systems and methods for antenna calibration

• US 8,049,662 B2
• Filed: 01/15/2008
• Issued: 11/01/2011
• Est. Priority Date: 07/23/2007
• Status: Active Grant

• Current Assignee: L3 Technologies, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: Aviation Communication and Surveillance Systems LLC (L3Harris Technologies, Inc.)
• Inventors: Stayton, Gregory T.
• Primary Examiner(s): Tarcza; Thomas
• Assistant Examiner(s): BYTHROW, PETER M
• Application Number:
  US12/014,666
• Publication Number:
  US 20090027258A1
• Time in Patent Office: 1,386 Days
• Field of Search: 342 29- 32, 342/165, 342/173, 342/174
• US Class Current: 342/174
• CPC Class Codes: G01S 13/781 Secondary Surveillance Radar [SSR] in general
• CPC Class Codes: G01S 13/933 of aircraft or spacecraft
• CPC Class Codes: G01S 7/4017 of HF systems
• CPC Class Codes: G01S 7/4026 Antenna boresight
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices

Abstract

A method according to an aspect of the present invention includes determining a phase offset by simultaneously providing a calibration signal to a first element of an antenna and a second element of the antenna opposite the first element. The method further includes receiving an intermix signal by a third element of the antenna, measuring an amplitude characteristic for the intermix signal, and determining a phase offset based on the amplitude characteristic. The phase offset can be used to adjust a signal provided to the first element so that signals transmitted from the first element and second element are in phase with each other. This method can account for phase errors due to the construction or design of the antenna, and allows antenna elements to be calibrated without the need for phase detector devices.

Claims

1. A method for determining a phase offset comprising:

simultaneously providing a calibration signal to a first element of an antenna and a second element of the antenna opposite the first element;

receiving a first intermix signal by a third element of the antenna;

measuring an amplitude characteristic for the first intermix signal;

determining the phase offset based on the amplitude characteristic;

receiving a second intermix signal by a fourth antenna element; and

measuring a second amplitude characteristic for the second intermix signal received by the fourth element;

wherein determining the phase offset comprises;

determining a first phase for the calibration signal from the first antenna element that produces a first predetermined amplitude characteristic for the first intermix signal;

determining a second phase for the calibration signal from the first antenna element that results in a second predetermined amplitude characteristic for the second intermix signal; and

employing a determined value of the first phase and a determined value of the second phase to determine the phase offset.

2. The method of claim 1, wherein determining the phase offset further comprises:

adding the determined value of the first phase to the determined value of the second phase and dividing the resulting sum by two.

3. The method of claim 1, wherein the first predetermined amplitude characteristic is the same as the second predetermined amplitude characteristic.

4. The method of claim 3, wherein the first predetermined amplitude characteristic and the second predetermined amplitude characteristic include at least one of a peak amplitude and a null amplitude.

5. The method of claim 1, further comprising adjusting a TCAS reply signal using the phase offset.

6. A system comprising:

a processor;

an antenna; and

a memory in communication with the processor and storing instructions that, when executed by the processor, cause the processor to;

simultaneously provide a calibration signal to a first element of the antenna and a second element of the antenna opposite the first element;

receive a first intermix signal by a third element of the antenna;

measure an amplitude characteristic for the first intermix signal; and

determine a phase offset based on the amplitude characteristic;

wherein the memory further stores instructions to cause the processor to;

receive a second intermix signal by a fourth antenna element; and

measure a second amplitude characteristic for the second intermix signal received by the fourth element;

wherein determining the phase offset comprises;

determining a first phase for the signal from the first antenna element that produces a first predetermined amplitude characteristic for the first intermix signal;

determining a second phase for the signal from the first antenna element that results in a second predetermined amplitude characteristic for the second intermix signal; and

employing a determined value of the first phase and a determined value of the second phase to determine the phase offset.

7. The system of claim 6, wherein the first, second, third, and fourth antenna elements are radially disposed around an axis of the antenna.

8. The system of claim 6, further comprising a beam-forming network coupled to the antenna.

9. The system of claim 8, wherein the beam-forming network is integrated with the antenna.

10. A method for determining a phase offset comprising:

simultaneously providing a calibration signal to a first element of an antenna, to a second element of the antenna opposite the first element, and to a third element of the antenna, wherein the calibration signal transmitted from the first antenna element is in phase with the calibration signal transmitted from the second antenna element;

receiving an intermix signal by a fourth element of the antenna;

measuring an amplitude characteristic for the intermix signal; and

determining the phase offset based on the amplitude characteristic;

wherein determining the phase offset includes determining a phase for the calibration signal from the third antenna element that produces a predetermined amplitude characteristic for the intermix signal and employing a determined value of the phase to determine the phase offset.

11. The method of claim 10, wherein predetermined amplitude characteristic includes at least one of a peak amplitude and a null amplitude.

12. The method of claim 10, wherein third element is opposite the fourth element.

13. The method of claim 10, further comprising adjusting a TCAS reply signal using the phase offset.

14. A system comprising:

a processor;

an antenna;

a memory in communication with the processor and storing instructions that, when executed by the processor, cause the processor to;

simultaneously provide a calibration signal to a first element of the antenna and a second element of the antenna opposite the first element, wherein the calibration signal transmitted from the first antenna element is in phase with the calibration signal transmitted from the second antenna element;

provide the calibration signal to a third element of the antenna;

receive an intermix signal by a fourth element of the antenna;

measure an amplitude characteristic for the intermix signal; and

determine a phase offset based on the amplitude characteristic;

wherein determining the phase offset includes determining a phase for the calibration signal from the third antenna element that produces a predetermined amplitude characteristic for the intermix signal and employing a determined value of the phase to determine the phase offset.

15. The system of claim 14, wherein the first, second, third, and fourth antenna elements are radially disposed around an axis of the antenna.

16. The system of claim 14, further comprising a beam-forming network coupled to the antenna.

17. The system of claim 16, wherein the beam-forming network is integrated with the antenna.