Method and apparatus for zooming and reconfiguring circular beams for satellite communications

• US 6,577,282 B1
• Filed: 07/19/2000
• Issued: 06/10/2003
• Est. Priority Date: 07/19/2000
• Status: Expired due to Fees

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Hsu, Chih-Chien, Voulelikas, George, Robinson, Stephen A., Rao, Sudhakar K.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Dinh, Trinh Vo
• Application Number:
  US09/619,042
• Time in Patent Office: 1,056 Days
• Field of Search: H01/Q 1.300, 343/781.CA, 343/781.P, 343/786, 343/772, 343/775, 343/840
• US Class Current: 343/781.0CA
• CPC Class Codes: H01Q 1/288 Satellite antennas
• CPC Class Codes: H01Q 19/19 comprising one main concave reflecting surface associated with an auxiliary reflecting surface
• CPC Class Codes: H01Q 3/18 wherein the primary active element is movable and the reflecting device is fixed

Abstract

A method and system for reconfiguring an antenna system are disclosed. The system comprises a feed horn, a subreflector, and a main reflector. The feed horn is pointed at an axis removed from the bisector axis of the subreflector. The distance between the feed horn and the subreflector can be changed to defocus the feed horn with respect to the subreflector, wherein a size of the outgoing beam emanating from the main reflector changes when the distance between the feed horn and the subreflector is changed. The method comprises pointing an axis of a feed horn at a subreflector, wherein the axis of the feed horn is aligned differently from the bisector axis of the subreflector, and changing the distance between the feed horn and the subreflector to defocus the feed horn with respect to the subreflector, wherein a size of an outgoing beam emanating from a main reflector changes when the distance between the feed horn and the subreflector is changed.

Claims

1. A reconfigurable antenna system, wherein the antenna system produces an outgoing beam of various sizes, comprising:

a feed horn;

a subreflector, wherein the feed horn is pointed at an axis tilted from a bisector axis of the subreflector; and

a main reflector;

a structure connecting the subreflector and the main reflector, the structure for changing a distance between the feed horn and the subreflector to defocus the feed horn with respect to the subreflector, wherein a size of the outgoing beam emanating from the main reflector changes when the distance between the feed horn and the subreflector is changed.

2. The system of claim 1, wherein the feed horn is moved and the subreflector and the main reflector remain stationary.

3. The system of claim 2, wherein the feed horn is moved using a linear actuator.

4. The system of claim 1, wherein the feed horn remains stationary and the subreflector and the main reflector are moved.

5. The system of claim 4, wherein the subreflector and the main reflector are moved using a linear actuator.

6. The system of claim 1, further comprising a mechanism, coupled to the main reflector, for moving the main reflector with respect to the subreflector and the feed horn.

7. The system of claim 6, wherein the mechanism moves the main reflector in azimuth and elevation directions with respect to the subreflector and the feed horn.

8. The system of claim 6, wherein the mechanism moves the main reflector to maintain a center of the outgoing beam substantially stationary when the distance between the feed horn and the subreflector is changed.

9. The system of claim 6, wherein the outgoing beam is pointed in a different direction using the mechanism to cover a different geographic area.

10. The system of claim 1, further comprising:

a second feed horn;

a second subreflector, wherein the second feed horn is pointed at an axis removed from a bisector axis of the second subreflector; and

a second main reflector, wherein a distance between the second feed horn and the second subreflector is changed to defocus the second feed horn with respect to the second subreflector, wherein a size of a second outgoing beam changes when the distance between the second feed horn and the subreflector is changed, and wherein the second outgoing beam is controlled independently of the outgoing beam.

11. The system of claim 1, wherein the outgoing beam is changed to increase the coverage area of the outgoing beam.

12. The system of claim 1, wherein the outgoing beam is changed to decrease the coverage area of the outgoing beam.

13. The system of claim 1, wherein the feed horn is located at a focal point of the subreflector.

14. The system of claim 1, wherein the feed horn is located away from a focal point of the subreflector and displaced in a transverse plane.

15. A method for communicating using a satellite, comprising:

selecting a geometry and a feed horn size for a desired zoomable range of an outgoing antenna beam;

pointing an axis of a feed horn at a subreflector, wherein the axis of the feed horn is tilted from the bisector axis of the subreflector;

selectively changing the distance between the feed horn and the subreflector to defocus the feed horn with respect to the subreflector, wherein a size of the outgoing beam emanating from a main reflector changes when the distance between the feed horn and the subreflector is changed; and

selecting an angle for a reflector gimbal mechanism based on a desired geographic location of the outgoing beam and a desired size of the outgoing beam.

16. Tithe method of claim 15, wherein the distance between the feed horn and the subreflector is changed by moving the feed horn.

17. The method of claim 15, wherein the distance between the feed horn and the subreflector is changed by moving the subreflector and the main reflector substantially simultaneously.

18. The method of claim 15, further comprising moving the main reflector with respect to the subreflector and the feed horn.

19. The method of claim 18, wherein the main reflector moves in azimuth and elevation directions with respect to the subreflector and the feed horn.

20. A reconfigurable antenna system, wherein the antenna system produces an outgoing beam of various sizes, comprising:

a feed horn;

a subreflector, wherein the feed horn is pointed at an axis tilted from a bisector axis of the subreflector; and

a gimbaled main reflector;

a structure connecting the subreflector and the main reflector, the structure selectably changing a distance between the feed horn and the subreflector to defocus the feed horn with respect to the subreflector, wherein a size of the outgoing beam emanating from the main reflector changes when the distance between the feed horn and the subreflector is changed.

21. The reconfigurable antenna system of claim 20, wherein the size of the outgoing beam emanating from the main reflector changes according to an aspect ratio of at least 1:

1.5 when the distance between the feed horn and the subreflector is changed.