Multi-band coaxial ring-focus antenna with co-located subreflectors

• US 20050099351A1
• Filed: 11/07/2003
• Published: 05/12/2005
• Est. Priority Date: 11/07/2003
• Status: Active Grant

• Current Assignee: North South Holdings Incorporated (Spherix Incorporated)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Kralovec, Jay A., Ortiz, Sean C., Gothard, Griffin K., Durham, Timothy E.
• Granted Patent: US 6,937,201 B2
• Time in Patent Office: Days
• US Class Current: 343/781.0CA
• CPC Class Codes: H01Q 15/0033 used for beam splitting or combining, e.g. acting as a quasi-optical multiplexer H01Q19/191 and H01Q19/195 take precedence
• CPC Class Codes: H01Q 19/193 with feed supported subreflector splash plate feeds H01Q19/134
• CPC Class Codes: H01Q 5/47 with a coaxial arrangement of the feeds

Abstract

A multi-band ring focus antenna system includes a main reflector (408) that is operable at a plurality spectrally offset frequency bands. A first feed (301, 403) includes a first feed horn (301) and a first sub-reflector (403), which are positioned spaced apart from each other at respective locations along a boresight axis of the main reflector. The locations are selected so that the first feed horn and the first sub-reflector share a commonly located first phase center (401). A second feed (302, 404) designed for operation on a second RF frequency band includes a second feed horn (302) and a second sub-reflector (404), each positioned at a location along the boresight axis of the main reflector so that they share a commonly located second phase center.

Claims

1. A method for multi-band operation of a ring focus antenna, comprising:

feeding a main reflector of said ring focus antenna on a first RF frequency band using a first feed horn spaced apart from a first sub-reflector along a boresight axis of said main reflector;

feeding said main reflector on a second RF frequency band spectrally offset from said first band using a second feed horn spaced apart from a second sub-reflector along said boresight axis;

co-locating a vertex of said first and second sub-reflector at a substantially equal distance from said main reflector to form with said first and second sub-reflectors a focal ring for each of said first and second bands at a common predetermined location spaced from said main reflector for concurrently illuminating said main reflector on said first and second bands; and

positioning said first and second feed horns so that the phase center of each feed horn is located at a respectively different distance from said co-located vertexes.

2. The method according to claim 1, further comprising the step of positioning at least a portion of said second feed horn coaxially within said first feed horn.

3. The method according to claim 1 further comprising the step of forming said first and second sub-reflectors so that each defines a shaped surface of revolution about said boresight axis of said main reflector having no continuous surface portion thereof shaped as a regular conical surface of revolution.

4. The method according to claim 3 further comprising the step of selecting said main reflector to define a shaped surface of revolution about said boresight axis having no continuous surface portion thereof shaped as a regular conical surface of revolution.

5. The method according to claim 1 further comprising the step of forming at least one of said first and second sub-reflectors as a frequency selective surface.

6. The method according to claim 1 further comprising the step of shaping said first sub-reflector to produce a phase center corresponding to a position of said phase center of said first horn and said second sub-reflector to produce a phase center corresponding to a position of said second horn.

7. The method according to claim 1 further comprising the step of forming said second sub-reflector as a frequency selective surface.

8. The method according to claim 1 further comprising the step of positioning each of said first feed horn and said second feed horn respectively at a distance from said first and second sub-reflectors so that they are decoupled.

9. A multi-band ring focus antenna system, comprising:

a main reflector operable at a plurality spectrally offset frequency bands;

a first feed for said main reflector for operation on a first RF frequency band, said first feed comprising a first feed horn spaced apart from a first sub-reflector along a boresight axis of said main reflector so that they share a commonly located first phase center;

a second feed for said main reflector for operation on a second RF frequency band spectrally offset from said first band, said second feed comprising a second feed horn spaced apart from a second sub-reflector along said boresight axis of said main reflector so that they share a commonly located second phase center; and

wherein a first and second vertexes of said respective first and second sub-reflectors are substantially co-located at an equal distance from said main reflector.

10. The multi-band ring-focus antenna system according to claim 9, wherein said first and second sub-reflectors each form a focal ring respectively for each of said first and second bands at a predetermined common location spaced from said main reflector.

11. The multi-band ring-focus antenna system according to claim 9 wherein at least a portion of said second feed horn is coaxially positioned within said first feed horn.

12. The multi-band ring-focus antenna system according to claim 9, wherein said first and second sub-reflectors each defines a shaped surface of revolution about said boresight axis of said main reflector having no continuous surface portion thereof shaped as a regular conical surface of revolution.

13. The multi-band ring-focus antenna system according to claim 9 wherein said main reflector defines a shaped surface of revolution about said boresight axis having no continuous surface portion thereof shaped as a regular conical surface of revolution.

14. The multi-band ring-focus antenna system according to claim 9 wherein at least one of said first and second sub-reflectors is a frequency selective surface.

15. The multi-band ring-focus antenna system according to claim 9 wherein said second sub-reflector is a frequency selective surface.

16. The multi-band ring-focus antenna system according to claim 9 wherein at least a portion of the shaped surface of revolution that comprises said second sub-reflector is interposed between said first horn and said first sub-reflector.

17. The multi-band ring-focus antenna system according to claim 16 wherein said second sub-reflector is a frequency selective surface

18. The multi-band ring-focus antenna system according to claim 9 wherein said first feed horn is a corrugated horn.

19. The multi-band ring-focus antenna system according to claim 9 wherein said second feed horn is a modal horn.

20. The multi-band ring-focus antenna system according to claim 9 wherein each of said first and second feed horns is decoupled from said first and second sub-reflectors.