System and method for transmitting signals via photonic excitation of a transmitter array

• US 7,898,464 B1
• Filed: 03/19/2007
• Issued: 03/01/2011
• Est. Priority Date: 04/11/2006
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Anderson, William W., Barquist, William S.
• Primary Examiner(s): Gregory; Bernarr E
• Application Number:
  US11/723,233
• Time in Patent Office: 1,443 Days
• Field of Search: 342 52- 54, 342 73-103, 342/175, 342368-377, 342/367, 342/195, 385/15, 385/31, 385 33- 35, 359/237, 359/238, 359/240, 359/245, 359/279, 359/298, 359/315, 359/316
• US Class Current: 342/54
• CPC Class Codes: H01Q 3/2676 Optically controlled phased array

Abstract

A radio frequency (RF) phased array transmitter system comprises a phased array for generating an RF signal. The phased array comprises conductive patches formed in an array, separation gaps, and active sources. Each of the separation gaps is formed between two adjacent ones of the conductive patches, and each of the active sources is formed across its associated one of the separation gaps. The system further comprises an optical source for generating an optical signal and an RF source for generating an RF signal. In addition, the system comprises an optical modulator coupled to the optical source and the RF source. The optical modulator receives an optical signal and an RF signal, and produces an RF modulated optical signal based on the received optical signal and the received RF signal.

Claims

1. A radio frequency (RF) phased array transmitter system comprising:

a phased array for generating an RF signal, the phased array comprising;

a plurality of conductive patches formed in an array such that a plurality of separation gaps are formed, wherein each of the plurality of separation gaps is formed between two adjacent ones of the plurality of conductive patches; and

a plurality of active sources, each of the plurality of active sources formed across its associated one of the plurality of separation gaps;

an optical source having an optical output, the optical source for generating an optical signal;

an RF source having an RF output, the RF source for generating an RF signal; and

an optical modulator coupled to the optical source and the RF source, the optical modulator having a first modulator input, a second modulator input and a modulator output, the first modulator input for receiving an optical signal, the second modulator input for receiving an RF signal, the modulator output for providing an RF modulated optical signal based on the received optical signal and the received RF signal.

2. The RF phased array transmitter system according to claim 1, wherein the phased array further comprises a plurality of inductors, each of the plurality of inductors comprises a first inductor connection and a second inductor connection, the first inductor connection of each one of the plurality of inductors is coupled to its associated one of the plurality of conductive patches, the second inductor connection of each one of the plurality of inductors is connected to either the positive or negative terminal of a voltage source, the polarity being chosen to maintain all photodiodes in reverse bias configuration.

3. The RF phased array transmitter system according to claim 2 further comprising a voltage source, wherein the second inductor connection of each one of the plurality of inductors is coupled to the voltage source.

4. The RF phased array transmitter system according to claim 3, wherein alternating ones of the plurality of inductors is coupled to a positive side of the voltage source, and the number of the plurality of inductors is equal to the number of the plurality of conductive patches.

5. The RF phased array transmitter system according to claim 2 further comprising a plurality of voltage sources, wherein the second inductor connection of each one of the plurality of inductors is coupled to its associated one of the plurality of voltage sources.

6. The RF phased array transmitter system according to claim 1 further comprising an optical divider coupled to the optical modulator, the optical divider having a divider input and divider outputs, the divider input for receiving an RF modulated optical signal, the divider outputs for providing a plurality of RF modulated optical signals to the phased array.

7. The RF phased array transmitter system according to claim 1, wherein each of the plurality of active sources comprises a current generator.

8. The RF phased array transmitter system according to claim 1, wherein each of the plurality of active sources comprises a photodiode.

9. The RF phased array transmitter system according to claim 8, wherein the polarity of the photodiodes alternates from one photodiode to next.

10. The RF phased array transmitter system according to claim 8, wherein the photodiodes are reversed biased.

11. The RF phased array transmitter system according to claim 1, wherein each of the plurality of conductive patches comprises a conductive area, and the conductive area covers an entire surface of its corresponding one of the plurality of conductive patches.

12. The RF phased array transmitter system according to claim 1, wherein a distance between a center of each one of the plurality of conductive patches and a center of an adjacent one of the plurality of conductive patches is less than half of the shortest wavelength of the RF signal generated by the phased array.

13. The RF phased array transmitter system according to claim 1, wherein the phased array is less than an inch in thickness.

14. The RF phased array transmitter system according to claim 1, wherein the phased array is shaped to conform to non-planar surfaces.

15. The RF phased array transmitter system according to claim 1 further comprising a plurality of optical couplings, each of the plurality of optical couplings coupled to its associated one of the plurality of active sources for optically addressing and controlling the associated one of the plurality of active sources.

16. The RF phased array transmitter system according to claim 1, wherein each of the plurality of separation gaps is formed between every two adjacent ones of the plurality of conductive patches, each of the plurality of active sources is coupled to two adjacent ones of the plurality of conductive patches, and the number of the plurality of separation gaps equals the number of the plurality of active sources.

17. The RF phased array transmitter system according to claim 1, wherein each of the plurality of conductive patches is square-shaped or rectangular-shaped.

18. A radio frequency (RF) transmitter system comprising:

a plurality of pattern elements comprising conductive areas, the plurality of pattern elements arranged such that a plurality of separation gaps are formed, wherein each of the plurality of separation gaps is formed between each set of adjacent ones of the plurality of pattern elements; and

a plurality of active sources, each of the plurality of active sources formed across its associated one of the plurality of separation gaps, wherein each of the plurality of active sources is operable to receive DC electrical power, each of the plurality of active sources is operable to receive an optical signal, and the plurality of active sources are operable to generate RF current.

19. The RF transmitter system according to claim 18, wherein each one of the plurality of active sources is coupled between its associated ones of the plurality of pattern elements, the electrical power is bias supply power, and the optical signal is an RF modulated optical signal from an optical modulator.

20. The RF transmitter system according to claim 18, wherein the optical signal is optical power, and the plurality of separation gaps are for radiating RF power.

21. A method for transmitting a radio frequency (RF) signal via photonic excitation of a transmitter, the method comprising steps of:

receiving an optical signal;

receiving an RF signal;

modulating the optical signal using the RF signal by an optical modulator;

receiving electrical power by a plurality of active sources of a transmitter;

receiving a modulated optical signal by the plurality of active sources of the transmitter;

generating RF current by the plurality of active sources; and

radiating RF power.

22. The method according to claim 21, wherein the plurality of active sources comprises photodiodes.

23. The method according to claim 21, wherein the modulated optical signal comprises a plurality of optical power, and each of the plurality of active sources receives its associated one of the plurality of optical power via an optical fiber.

24. The method according to claim 21, wherein the transmitter further comprises:

a plurality of conductive patches formed in an array such that a plurality of separation gaps are formed, wherein each of the plurality of separation gaps is formed between two adjacent ones of the plurality of conductive patches, and each of the plurality of active sources is formed across its associated one of the plurality of separation gaps.

25. The method according to claim 24, wherein each of the plurality of separation gaps radiates RF power, and

wherein the step of radiating RF power comprises generating photovoltages that are in-phase across the plurality of separation gaps.

26. The method according to claim 24, wherein the plurality of separation gaps are excited by coherently phased currents.