System and Method for Adaptive Correction to Phased Array Antenna Array Coefficients Through Dithering and Near-Field Sensing

• US 20110205117A1
• Filed: 02/19/2010
• Published: 08/25/2011
• Est. Priority Date: 02/19/2010
• Status: Active Grant

• Current Assignee: Newlans, Inc. (Royal KPN NV), University Of Massachusetts
• Original Assignee: Newlans, Inc. (Royal KPN NV)
• Inventors: Gupta, Dev Vrat, Janaswamy, Ramakrishna
• Granted Patent: US 8,299,964 B2
• Time in Patent Office: Days
• US Class Current: 342/372
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
• CPC Class Codes: H01Q 3/2652 Self-phasing arrays

Abstract

A system and method of adaptively correcting the excitation or receive coefficients for a phased array antenna. For a transmitting antenna, a sensor located in the near field of the antenna is used to sense the antenna transmission. A reference signal that represents the sensor response to a desired antenna transmission that is accomplished with predetermined excitation coefficients is determined. The magnitudes and phases of the excitation coefficients are modified in a predetermined manner to create a modified antenna transmission. An actual signal that represents the sensor response to the modified antenna transmission is then determined. The excitation coefficients are then corrected using the differences between the reference signal and the actual signal, such that the modified antenna transmission becomes closer to the desired antenna transmission. The method and system also apply to a receiving antenna.

Claims

1. A method of adaptively correcting the excitation or receive coefficients for a phased array antenna that comprises a plurality of antenna elements, comprising:

locating one or more sensors or transmitting antennas in the near field of the phased array antenna, the sensor for sensing the phased array antenna transmission, and the transmitting antenna for transmitting a signal that is received by the phased array antenna;

determining a reference signal that represents either the sensor response to a desired phased array antenna transmission that is accomplished with predetermined excitation coefficients or the transmitting antenna transmission that results in a desired phased array antenna reception that would be accomplished with predetermined receive coefficients;

modifying the magnitudes and phases of the coefficients in a predetermined manner to create a modified phased array antenna transmission or reception;

determining an actual signal that represents either the sensor response to the modified transmission or the phased array antenna output with the modified coefficients; and

correcting the coefficients in a manner that is based on the reference signal and the actual signal, such that either the modified phased array antenna transmission becomes closer to the desired transmission or the modified phased array antenna reception becomes closer to the desired reception.

2. The method of claim 1 in which the modifying step comprises modifying the coefficients for each element of the array.

3. The method of claim 2 in which the modifying step further comprises dithering the coefficients by independently fluctuating their magnitude and the phase for each element of the array.

4. The method of claim 3 in which the fluctuations are independent from element to element.

5. The method of claim 1 in which the correcting step comprises determining an error signal based on a complex conjugation of the difference between the actual signal and the reference signal.

6. The method of claim 5 in which the correcting step further comprises minimizing the error signal.

7. The method of claim 6 in which the error signal is minimized using a gradient-based algorithm.

8. The method of claim 7 in which the algorithm uses all states of the total component of the modified antenna transmission at the sensor.

9. The method of claim 7 in which the algorithm uses all states of the total component of the modified phased array antenna reception.

10. The method of claim 5 in which the correcting step further comprises minimizing a gradient of the error signal.

11. The method of claim 1 in which the reference signal is predetermined and then stored in memory for use in the adaptive correction.

12. A system for adaptively correcting the excitation or receive coefficients for a phased array antenna that comprises a plurality of antenna elements, comprising:

one or more sensors or transmitting antennas located in the near field of the phased array antenna, the sensor sensing the phased array antenna transmission, and the transmitting antenna transmitting a signal that is received by the phased array antenna;

a memory that stores a reference signal that represents either the sensor response to a desired phased array antenna transmission that is accomplished with predetermined excitation coefficients or the transmitting antenna transmission that results in a desired phased array antenna reception that would be accomplished with predetermined receive coefficients;

a processor that modifies the magnitudes and phases of the coefficients in a predetermined manner to create a modified phased array antenna transmission or reception, determines an actual signal that represents either the sensor response to the modified transmission or the phased array antenna output with the modified coefficients, and corrects the coefficients in a manner that is based on the reference signal and the actual signal, such that either the modified phased array antenna transmission becomes closer to the desired transmission or the modified phased array antenna reception becomes closer to the desired reception.

13. The system of claim 12 in which the coefficients for each element of the array are modified under control of the processor.

14. The system of claim 13 in which the magnitude and the phase of the coefficients for each element of the array are independently fluctuated.

15. The system of claim 14 in which the fluctuations are independent from element to element.

16. The system of claim 12 in which the correction is accomplished by determining an error signal based on a complex conjugation of the difference between the actual signal and the reference signal.

17. The system of claim 16 in which the correction is further accomplished by minimizing the error signal.

18. The system of claim 17 in which the error signal is minimized using a gradient-based algorithm.

19. The system of claim 18 in which the algorithm uses all states of the total component of the modified phased array antenna transmission at the sensor.

20. The system of claim 12 in which the algorithm uses all states of the total component of the modified phased array antenna reception.

21. The system of claim 16 in which the correction is further accomplished by minimizing a gradient of the error signal.

22. The system of claim 12 in which the reference signal is predetermined and then stored in the memory.