RF receiver front-end assembly

• US 8,750,709 B1
• Filed: 07/18/2008
• Issued: 06/10/2014
• Est. Priority Date: 07/18/2008
• Status: Active Grant

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: Schaffner, James H., Yap, Daniel
• Primary Examiner(s): CURS, NATHAN M
• Application Number:
  US12/176,114
• Time in Patent Office: 2,153 Days
• Field of Search: 398115-117
• US Class Current: 398/117
• CPC Class Codes: H01P 5/12 Coupling devices having more than two ports H01P5/04 takes precedence
• CPC Class Codes: H01Q 13/02 Waveguide horns
• CPC Class Codes: H04B 10/90 Non-optical transmission systems, e.g. transmission systems employing non-photonic corpuscular radiation
• CPC Class Codes: H04B 2210/006 Devices for generating or processing an RF signal by optical means

Abstract

A waveguide of radio frequency electromagnetic fields is multi-furcated into a plurality of radio frequency waveguide sections, each radio frequency waveguide section having an optoelectronic modulator electrically coupled to it. Each optoelectronic modulator has an optical waveguide disposed therein such that, in use, light traveling in the optical waveguides of the optoelectronic modulators travels in a direction orthogonal with respect to the direction the radio frequency electromagnetic field travels in the radio frequency waveguide sections. The plurality of radio frequency waveguide sections are fed from a common source of said radio frequency energy. In some embodiments, each radio frequency waveguide section has a dielectric material having a length and/or a dielectric constant selected such that a relative time delay of the radio frequency energy propagating in the radio frequency waveguide sections accommodates for a time delay of the light traveling from one optoelectronic modulator to a next optoelectronic modulator of a series connection of multiple optoelectronic modulators.

Claims

1. A multi-furcated structure responsive to input radio-frequency electromagnetic radiation comprising:

a plurality of radio frequency waveguide sections, at least one end of each radio frequency waveguide section being physically in contact with or adjacent one end of at least one other radio frequency waveguide section of said plurality of radio frequency waveguide sections, wherein each radio frequency waveguide section couples a different spatial portion of the input electromagnetic radiation, the plurality of radio frequency waveguide sections being fed from a common source of said radio frequency electromagnetic radiation;

each radio frequency waveguide section having an optoelectronic modulator electrically and physically coupled to it, wherein each optoelectronic modulator responds to the electromagnetic radiation coupled to it by the radio frequency waveguide section to which that optoelectronic modulator is electrically coupled and physically connected;

each optoelectronic modulator having an optical waveguide disposed therein such that, in use, light traveling in the optical waveguides of said optoelectronic modulators travels in a direction orthogonal with respect to the radio frequency energy propagating in said radio frequency waveguide sections; and

wherein each optoelectronic modulator has the optical waveguide disposed therein such that, in use, light traveling in the optical waveguides of said optoelectronic modulators (i) travels in a direction orthogonal with respect to the radio frequency energy propagating in said radio frequency waveguide sections and (ii) is responsive to the orthogonally traveling radio frequency energy.

2. The multi-furcated structure of claim 1 wherein each radio frequency waveguide section has dielectric material having a length and/or a dielectric constant selected time delay so that a relative delay of the radio frequency electromagnetic radiation propagating in the radio frequency waveguide sections accommodates for a time delay of the light traveling between the optoelectronic modulators.

3. The multi-furcated structure of claim 2 wherein the plurality of radio frequency waveguide sections all are filled with dielectric filler material having the same value for the dielectric constant.

4. The multi-furcated structure of claim 3 wherein a first radio frequency waveguide section of the plurality of radio frequency waveguide sections contains a dielectric material having a first length and a second radio frequency waveguide section of the plurality of radio frequency waveguide sections contains a dielectric material having a second length, wherein said first length and said second length are different.

5. The multi-furcated structure of claim 2 wherein a first radio frequency waveguide section of the plurality of radio frequency waveguide sections contains a dielectric material having a first value for its dielectric constant and a second radio frequency waveguide section of the plurality of radio frequency waveguide sections contains a dielectric material having a second value for its dielectric constant, wherein said first value and said second value are different.

6. The multi-furcated structure of claim 1 further including an impedance matching structure disposed between said common source of said radio frequency energy and said plurality of radio frequency waveguide sections.

7. The multi-furcated structure of claim 1 wherein the plurality of radio frequency waveguide sections are transverse electromagnetic waveguides disposed parallel to each other and have parallel metallic walls for which, when two of said radio frequency waveguide sections are immediately adjacent one another, one of said metallic walls of one of said immediately adjacent radio frequency waveguide sections confronts one of said metallic walls of the other one of said immediately adjacent radio frequency waveguide sections.

8. The multi-furcated structure of claim 1 wherein the plurality of radio frequency waveguide sections are transverse electromagnetic waveguides disposed parallel to each other and have parallel metallic walls for which, when two of said radio frequency waveguide sections are immediately adjacent, one of said metallic walls of one of said immediately adjacent radio frequency waveguide sections is shared as one of said metallic walls of the other one of said immediately adjacent radio frequency waveguide sections.

9. The multi-furcated structure of claim 1 in combination with a horn antenna wherein the horn antenna provides the common source of said radio frequency energy.

10. The multi-furcated structure and horn antenna combination of claim 9 wherein exterior-most metallic surfaces of said plurality of radio frequency waveguide sections are electrically connected to opposing metallic surfaces of said horn antenna.

11. The multi-furcated structure of claim 1 wherein at least a first and a second optoelectronic modulator of said optoelectronic modulators are disposed on a common substrate and wherein said common substrate is physically attached to one of the radio frequency waveguide sections coupled to said first optoelectronic modulator and said common substrate also is physically attached to another of the radio frequency waveguide sections coupled to said second optoelectronic modulator.

12. The multi-furcated structure of claim 11 wherein said common substrate further includes optical waveguide bends for establishing a different separation between (a) portions of optical waveguides disposed in said optoelectronic modulators and (b) portions of optical waveguides located at or near an edge of said common substrate, said portions of optical waveguides located at the edge of said common substrate conducting light between optical fibers and said optoelectronic modulators.

13. The multi-furcated structure of claim 11 wherein said common substrate further includes at least one metal filled via hole or metal coated via hole, said at least one metal filled or metal coated via hole conducting an electrical current from a first radio frequency waveguide section physically connected to one side of said common substrate to a second radio frequency waveguide section physically connected to another, opposing side of said common substrate.

14. The multi-furcated structure of claim 1 wherein the plurality of radio frequency waveguide sections are dielectric waveguides disposed parallel to each other and have a gap between each pair of immediately adjacent dielectric waveguides, wherein the gap is filled with a material whose dielectric constant is smaller than the dielectric constant of dielectric material comprising the plurality of radio frequency waveguide sections.

15. The multi-furcated structure of claim 1 wherein the plurality of radio frequency waveguide sections comprise dielectric material, with no gap occurring between the dielectric material of immediately adjacent radio frequency waveguide sections of the plurality of radio frequency waveguide sections, said plurality of radio frequency waveguide sections acting as a unity radio frequency dielectric waveguide.

16. The multi-furcated structure of claim 1 wherein the plurality of radio frequency waveguide sections are dielectric waveguides, wherein immediately adjacent radio frequency waveguide sections approach or contact each other at least at a first point or points along a length of said radio frequency waveguide sections and wherein the adjacent radio frequency waveguide sections are separated by an increasing gap at second points spaced from said first point or points.

17. The multi-furcated structure of claim 1 wherein a first optoelectronic modulator of said optoelectronic modulators receives light from a laser source and supplies light to a second optoelectronic modulator of said optoelectronic modulators, said first optoelectronic modulator and said second optoelectronic modulator being coupled to different radio frequency waveguide sections of said plurality of radio frequency waveguide sections.

18. The multi-furcated structure of claim 17 wherein said first optoelectronic modulator couples light to an optical amplifier and said optical amplifier couples amplified light to said second optoelectronic modulator.

19. The multi-furcated structure of claim 1 in combination with a dish antenna wherein the dish antenna provides the common source of said radio frequency energy.

20. The multi-furcated structure of claim 1 in combination with a dielectric rod antenna wherein the dielectric rod antenna provides the common source of said radio frequency energy.

21. The multi-furcated structure of claim 1 wherein each radio frequency waveguide section is a dielectric radio frequency waveguide section.

22. A method for sensing incident electromagnetic radiation comprising the steps of:

coupling a first spatial portion of an electromagnetic field of said incident electromagnetic radiation into a first radio frequency waveguide section and coupling a second spatial portion of the electromagnetic field of said incident electromagnetic radiation into a second radio frequency waveguide section;

propagating the electromagnetic field coupled into said first radio frequency waveguide section in a first direction through said first radio frequency waveguide section to a first optoelectronic modulator located on a modulator substrate and propagating the electromagnetic field coupled into said second radio frequency waveguide section in a second direction through said second radio frequency waveguide section to a second optoelectronic modulator located on said modulator substrate;

propagating light through said first optoelectronic modulator in a first orthogonal direction disposed orthogonally to the first direction that said electromagnetic field propagates through said first radio frequency waveguide section and propagating light through said second optoelectronic modulator in a second orthogonal direction disposed orthogonally to the second direction that said electromagnetic field propagates through said second radio frequency waveguide section;

modulating the light propagating through said first optoelectronic modulator according to a time-varying electric field component of said electromagnetic field propagating in said first direction to said first optoelectronic modulator, and modulating the light propagating through said second optoelectronic modulator according to a time-varying electric field component of said electromagnetic field propagating in said second direction to said second optoelectronic modulator; and

wherein the step of modulating the light propagating through said first optoelectronic modulator according to said time-varying electric field component of said electromagnetic field propagating in said first direction to said first optoelectronic modulator occurs in said first orthogonal direction, and wherein the step of modulating the light propagating through said second optoelectronic modulator according to the time-varying electric field component of said electromagnetic field propagating in said second direction to said second optoelectronic modulator occurs in said second orthogonal direction.

23. The method of claim 22 further comprising propagating modulated light produced at said first optoelectronic modulator to said second optoelectronic modulator for modulation by said second optoelectronic modulator.

24. The method of claim 22 further comprising applying a time delay to said electromagnetic field propagating through said second radio frequency waveguide section such that said time delay is matched to a time delay of the light propagating through said first optoelectronic modulator plus a time delay of the light propagating from said first optoelectronic modulator to said second optoelectronic modulator.

25. The method of claim 22 further comprising photodetecting the modulated light produced by said first optoelectronic modulator to generate a first radio frequency signal and photodetecting the modulated light produced by said second optoelectronic modulator to generate a second radio frequency signal;

and combining said first and second radio frequency signals.

26. The method of claim 22 wherein the first and second directions are non-parallel directions.

27. The method of claim 22 wherein the first and second radio frequency waveguide sections each comprise at least one dielectric waveguide.

28. A multi-furcation structure comprising:

a plurality of optoelectronic modulators and a furcated waveguide for distributing incident electromagnetic radiation into a plurality of different waveguide sections forming said furcated waveguide, each different waveguide section coupling a different spatial portion of the incident electromagnetic radiation to a different one of said plurality of optoelectronic modulators and wherein each one of said waveguide sections is disposed in contact with at least another one of said waveguide sections.

29. The multi-furcation structure of claim 28 wherein each optoelectronic modulator has an optical waveguide disposed therein such that, in use, light traveling in the optical waveguides of said optoelectronic modulators travels in a direction orthogonal with respect to the different spatial portion of the incident electromagnetic radiation propagating in each of the waveguide sections.

30. The multi-furcation structure of claim 29 wherein each different waveguide section has first and second portions, the first portions of the different waveguide sections being disposed parallel to each other and the second portions of the different waveguide sections being disposed in a diverging relationship with resect to each other.

31. The multi-furcation structure of claim 30 wherein at least one of said optoelectronic modulators is disposed between the first and second portions of the each of the different waveguide sections.

32. The multi-furcated structure of claim 28 wherein each waveguide section is a dielectric waveguide forming said furcated waveguide and wherein each one of said waveguide sections is disposed in contact with at least another one of said waveguide sections.

33. The multi-furcated structure of claim 28 wherein each one of said waveguide sections is disposed in contact with at least another one of said waveguide sections at first ends thereof and wherein each one of said waveguide sections is disposed spaced a distance away from at least another one of said waveguide sections at second ends thereof.

34. The multi-furcated structure of claim 33 wherein the plurality of optoelectronic modulators is disposed at the second ends of the waveguide sections.

35. The multi-furcated structure of claim 28 wherein the incident electromagnetic radiation is applied to a impedance matching structure which is in immediate contact with said furcated waveguide.

36. The multi-furcated structure of claim 35 wherein each waveguide section comprises a reduced height waveguide.

37. The multi-furcated structure of claim 28 wherein each waveguide section comprises a reduced height waveguide.

38. The multi-furcated structure of claim 28 wherein each waveguide section comprises a reduced height waveguide and wherein the reduced height of each waveguide tapers in height over at least a portion of a length of each waveguide section.

39. A multi-furcated structure responsive to input electromagnetic radiation comprising:

a plurality of TEM waveguide sections, at least one end of each TEM waveguide section being physically in contact with or adjacent one end of at least one other TEM waveguide section of said plurality of TEM waveguide sections, wherein each TEM waveguide section couples a different spatial portion of the input electromagnetic radiation, the plurality of TEM waveguide sections being fed from a common source of said input electromagnetic radiation;

each TEM waveguide section having an optoelectronic modulator electrically and physically coupled to it, wherein each optoelectronic modulator responds to the electromagnetic radiation coupled to it by the TEM waveguide section to which that optoelectronic modulator is electrically coupled and physically connected;

each optoelectronic modulator having an optical waveguide disposed therein such that, in use, light traveling in the optical waveguides of said optoelectronic modulators travels in a direction orthogonal with respect to the electromagnetic radiation propagating in said TEM waveguide sections.