CASSEGRAIN RADAR ANTENNA WITH SELECTABLE ACQUISITION AND TRACK MODES

• US 3,795,004 A
• Filed: 02/26/1973
• Issued: 02/26/1974
• Est. Priority Date: 02/26/1973
• Status: Expired due to Term

• Current Assignee: Clarence F. Ravilious, James M. Meek, Whilden G. Heinard
• Original Assignee: Clarence F. Ravilious, James M. Meek, Whilden G. Heinard
• Inventors: Meek, James M., Ravilious, Clarence F., Heinard, Whilden G.
• Primary Examiner(s): Borchelt, Archie R.
• Assistant Examiner(s): Nussbaum, Marvin
• Application Number:
  US05/335,877
• Time in Patent Office: 365 Days
• Field of Search: 343/777,779,781,761,757,758,835,837,839
• US Class Current: 343/761
• CPC Class Codes: H01Q 19/18 having two or more spaced reflecting surfaces H01Q19/20 takes precedence
• CPC Class Codes: H01Q 19/191 wherein the primary active element uses one or more deflecting surfaces, e.g. beam waveguide feeds
• CPC Class Codes: H01Q 3/18 wherein the primary active element is movable and the reflecting device is fixed
• CPC Class Codes: H01Q 3/245 in the focal plane of a focussing device

Abstract

A Schwarzschild Antenna cooperates with an organ pipe scanner to achieve wide angle sectoral scanning of a high gain pencil beam. A rotatable mirror switches the antenna to conical scanning whereby microwave energy communicates between a nutating horn and reflectors of the Schwarzschild Antenna. During conical scanning, the organ pipe scanner remains unenergized. The mode of operation is selectable by the operator and the system is designed for rapid switching.

Claims

1. A Schwarzschild antenna system comprising:

reflector means for reflecting microwave energy that impinges thereon;

scanner means adjacent the reflector means and communicating with the reflector means for producing a wide angle unidirectional sectoral scan;

horn means disposed in adjacent spaced relationship to the reflector means and communicating with the reflector means for producing a narrow angle scan; and

microwave switching means mounted adjacent to the reflector means to selectively complete microwave communication between the reflector means and either the scanner means or the horn means;

whereby the switching means enables rapid selection of the sectoral scan or the narrow angle scan.

2. The structure of claim 1 wherein the scanner means comprises a plurality of adjacently spaced feEd horns communicating with respective waveguide pipes to form an organ pipe scanner which produces a unidirectional scan across the outlet ends of the feedhorns.

3. The structure of claim 1 wherein the horn means comprises at least a single nutating horn for conical scan tracking.

4. The subject matter of claim 1 wherein the horn means is a multi-port assembly comprising a plurality of adjacently positioned stationary horns for operating in a steady track mode.

5. The structure of claim 2 wherein the switching means comprises a movably mounted flat mirror reflector positioned in intermediate relation between the scanner means and the horn means for selectably communicating microwave energy between the reflector means and either the scanner means or the horn means.

6. The subject matter of claim 2 wherein each of the feed horns has a pyramidal shape.

7. The structure of claim 3 wherein each of the horn means has a pyramidal shape.

8. The subject matter of claim 2 and further wherein the horn means comprises at least a single nutating horn for conical scan tracking.

9. The subject matter of claim 5 wherein the mirror is longitudinally mounted to a shaft to permit selectable rapid rotation of the mirror between two angular positions.

10. The subject matter of claim 9 wherein the shaft is connected to a torquer that selectably drives the shaft between the two angular positions in response to electrical energization of the torquer.