ANTENNA WITH INTEGRATED TUNING DETECTION ELEMENTS

• US 20100248649A1
• Filed: 09/15/2009
• Published: 09/30/2010
• Est. Priority Date: 03/30/2009
• Status: Active Grant

• Current Assignee: Charles Stark Draper Laboratory Incorporated
• Original Assignee: Charles Stark Draper Laboratory Incorporated
• Inventors: White, Douglas W.
• Granted Patent: US 8,472,904 B2
• Time in Patent Office: Days
• US Class Current: 455/77
• CPC Class Codes: H03J 3/20 of single resonant circuit by varying inductance only or capacitance only

Abstract

In various embodiments, systems and methods for automatically tuning an antenna to a desired frequency utilize a tuning detection element that sends or receives a signal in accordance with one mode of the antenna and that is separated from the antenna by a gap and outside of a signal path of the antenna. In various system implementations, a processor communicates with the tuning detection element and antenna and monitors the amplitude of a signal transmitted to or from the tuning detection element. A resonant frequency of the antenna may be tuned to the desired frequency by a tuning element.

Claims

1. A system for automatically tuning an antenna to a desired frequency, the antenna having a signal path for receiving a signal, the system comprising:

a tuning detection element, located outside of the signal path and separated from the antenna by a gap, for transmitting a signal to the antenna in accordance with at least one mode of the antenna;

a processor for monitoring an amplitude of the signal received by the antenna; and

a tuning element for tuning a resonant frequency of the antenna to the desired frequency based on an instruction from the processor.

2. The system of claim 1, wherein the instruction from the processor maximizes the received signal.

3. The system of claim 1, wherein the tuning element is located outside of the signal path.

4. The system of claim 1, further comprising a low-noise amplifier in the signal path.

5. The system of claim 1, further comprising a feedback path for transmitting a portion of an output of the signal path to the processor.

6. The system of claim 1, further comprising a driver circuit for driving the tuning detection element with the transmitted signal.

7. The system of claim 1, further comprising at least one additional tuning detection element for operation in accordance with at least one additional mode of the antenna.

8. The system of claim 7, wherein the signal path communicates a circularly polarized signal.

9. The system of claim 8, wherein the instruction from the processor minimizes the received signal.

10. The system of claim 1, wherein the antenna is at least one of a patch antenna, a planar inverted-F antenna, a monopole antenna, or a dipole antenna.

11. The system of claim 1, wherein the tuning element comprises at least one of a variable-capacitance device or a variable-inductance device.

12. The system of claim 1, wherein the tuning element comprises at least one of a varactor diode, a switched metal element, or a switched capacitor.

13. A method for automatically tuning an antenna to a desired frequency, the method comprising:

radiating energy proximate an antenna outside of a signal path, the energy radiated in accordance with at least one mode of the antenna;

receiving a signal from the antenna in response to the energy radiated in accordance with the at least one mode;

monitoring an amplitude of the received signal; and

tuning a resonant frequency of the antenna to the desired frequency with a tuning element based on the monitored amplitude.

14. The method of claim 13, wherein tuning the antenna comprises maximizing the amplitude of the received signal.

15. The method of claim 13, further comprising radiating additional energy in accordance with at least one additional mode of the antenna.

16. The method of claim 15, wherein the antenna is tuned to receive a circularly polarized signal.

17. The method of claim 16, wherein tuning the antenna comprises minimizing the amplitude of the received signal.

18. The method of claim 13, wherein the antenna is tuned by a tuning element located outside of the signal path.

19. The method of claim 13, wherein the antenna is at least one of a patch antenna, a planar inverted-F antenna, a monopole antenna, and a dipole antenna.

20. The method of claim 13, wherein the tuning element comprises at least one of a variable inductance device or a variable capacitance device.

21. The method of claim 13, wherein the tuning element comprises at least one of a varactor diode, a switched metal element, or a switched capacitor.

22. A system for automatically tuning an antenna to a desired frequency, the antenna having a signal path for transmitting a signal, the system comprising:

a tuning detection element, located outside of the signal path and separated from the antenna by a gap, for receiving a signal transmitted from the antenna in accordance with at least one mode of the antenna;

a processor for monitoring an amplitude of the signal received by the tuning detection element; and

a tuning element for tuning a resonant frequency of the antenna to the desired frequency based on an instruction from the processor.

23. The system of claim 22, wherein the instruction from the processor maximizes the received signal.

24. The system of claim 22, wherein the tuning element is located outside of the signal path.

25. The system of claim 22, further comprising a feedback path for transmitting a portion of an output of the signal path to the processor.

26. The system of claim 22, further comprising a receiver circuit for receiving the signal from the tuning detection element.

27. The system of claim 22, further comprising at least one additional tuning detection element for operation in accordance with at least one additional mode of the antenna.

28. The system of claim 27, wherein the signal path communicates a circularly polarized signal.

29. The system of claim 28, wherein the instruction from the processor minimizes the received signal.

30. The system of claim 22, wherein the antenna is at least one of a patch antenna, a planar inverted-F antenna, a monopole antenna, and a dipole antenna.

31. The system of claim 22, wherein the tuning element comprises at least one of a variable-inductance device or a variable-capacitance device.

32. The system of claim 22, wherein the tuning element comprises at least one of a varactor diode, a switched metal element, or a switched capacitor.

33. A method for automatically tuning an antenna to a desired frequency, the method comprising:

transmitting a signal to an antenna over a signal path, the antenna radiating energy in accordance with at least one mode of the signal;

receiving energy radiated from the antenna at a tuning detection element located outside of the signal path;

monitoring an amplitude of the received energy in accordance with the at least one mode of the signal; and

tuning a resonant frequency of the antenna to the desired frequency with a tuning element based on the monitored amplitude.

34. The method of claim 33, wherein tuning the antenna comprises maximizing the amplitude of the received energy.

35. The method of claim 33, further comprising receiving additional energy radiated from the antenna in accordance with at least one additional mode of the signal.

36. The method of claim 35, wherein the antenna is tuned to transmit a circularly polarized signal.

37. The method of claim 36, wherein tuning the antenna comprises minimizing the amplitude of the received energy.