Antenna with integrated tuning detection elements

• US 8,472,904 B2
• Filed: 09/15/2009
• Issued: 06/25/2013
• 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.
• Primary Examiner(s): HUANG, WEN WU
• Application Number:
  US12/559,687
• Publication Number:
  US 20100248649A1
• Time in Patent Office: 1,379 Days
• Field of Search: 455/193.1, 455/193.2, 455/193.3, 455/272, 455/273, 455/274, 455/120, 455/121, 455/123, 455/125
• US Class Current: 455/193.1
• 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 a multi-mode antenna to a desired frequency, the antenna having a signal path for receiving a signal, the system comprising:

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

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 and is not in direct electrical communication therewith.

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. The system of claim 1, wherein a resonant frequency of the tuning detection element is non-overlapping with a frequency band of the antenna.

14. A method for automatically tuning a multi-mode antenna to a desired frequency, the method comprising:

radiating energy proximate the antenna from a tuning detection element that is;

(i) coupled to at least one mode of the antenna, (ii) uncoupled from at least one other mode of the antenna, and (iii) located outside of a signal path of the antenna and separated from the antenna by a gap, the energy being radiated in accordance with at least one mode of the antenna to which the tuning detection element is coupled;

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.

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

16. The method of claim 14, further comprising radiating additional energy in accordance with at least one additional mode of the antenna.

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

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

19. The method of claim 14, wherein the antenna is tuned by a tuning element that is located outside of the signal path and that is not in direct electrical communication therewith.

20. The method of claim 14, wherein the antenna is at least one of a patch antenna, a planar inverted-F antenna, a monopole antenna, and a dipole antenna.

21. The method of claim 14, wherein the tuning element comprises at least one of a variable inductance device or a variable capacitance device.

22. The method of claim 14, wherein the tuning element comprises at least one of a varactor diode, a switched metal element, or a switched capacitor.

23. The method of claim 14, wherein the tuning detection element has a resonant frequency that is non-overlapping with a frequency band of the antenna.

24. A system for automatically tuning a multi-mode antenna to a desired frequency, the antenna having a signal path for transmitting a signal, the system comprising:

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

a processor for monitoring an amplitude of the signal received by the tuning detection element and for generating a tuning instruction based on the monitored amplitude; and

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

25. The system of claim 24, wherein the instruction from the processor maximizes the received signal.

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

27. The system of claim 24, further comprising a feedback path for transmitting a portion of an output of the signal path to the processor.

28. The system of claim 24, further comprising a receiver circuit for receiving the signal from the tuning detection element.

29. The system of claim 24, further comprising at least one additional tuning detection element for operation in accordance with at least one additional mode of the antenna.

30. The system of claim 29, wherein the signal path communicates a circularly polarized signal.

31. The system of claim 30, wherein the instruction from the processor minimizes the received signal.

32. The system of claim 24, wherein the antenna is at least one of a patch antenna, a planar inverted-F antenna, a monopole antenna, and a dipole antenna.

33. The system of claim 24, wherein the tuning element comprises at least one of a variable-inductance device or a variable-capacitance device.

34. The system of claim 24, wherein the tuning element comprises at least one of a varactor diode, a switched metal element, or a switched capacitor.

35. A method for automatically tuning a multi-mode antenna to a desired frequency, the method comprising:

transmitting a signal to the antenna over a signal path, thereby causing the antenna to radiate energy in accordance with at least one mode of the antenna;

receiving the energy radiated from the antenna at a tuning detection element that is;

(i) coupled to at least one mode of the antenna, (ii) uncoupled from at least one other mode of the antenna, and (iii) located outside of the signal path, the received energy having been radiated from the antenna in accordance with at least one mode of the antenna to which the tuning detection element is coupled;

monitoring an amplitude of the received energy; and

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

36. The method of claim 35, wherein tuning the antenna comprises maximizing the amplitude of the received energy.

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

38. The method of claim 37, wherein the antenna is tuned to transmit a circularly polarized signal.

39. The method of claim 38, wherein tuning the antenna comprises minimizing the amplitude of the received energy.

40. A system for automatically tuning an antenna to a desired frequency, the system comprising:

a substrate having disposed thereon (i) an antenna having a signal path for receiving a signal, and (ii) a tuning detection element, having a resonant frequency that is non-overlapping with a frequency band of the antenna, for transmitting a signal to the antenna, the tuning detection element located outside of the signal path and separated from the antenna by a gap;

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.

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

radiating energy proximate an antenna disposed on a substrate from a tuning detection element disposed on the substrate, the tuning detection element (i) having a resonant frequency that is non-overlapping with a frequency band of the antenna, and (ii) located outside of a signal path of the antenna and separated from the antenna by a gap;

receiving a signal from the antenna in response to the radiated energy;

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.