Variable beamwidth antenna

US3938162A · kind A · utility

Assignee

• The United States of America as represented by the United States National Aeronautics and Space Administration Office of General Counsel-Code GP · US

Inventor

• Richard Schmidt · Kiel, DE

Key dates

• Filing date: Aug 27, 1974
• Grant date: Feb 10, 1976
• Expiry date: Aug 27, 1994

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01Q25/002
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

Abstract

An antenna system for single or plural beams providing continuously variable beamwidth selectively in one or both of two orthogonal senses, i.e., azimuth and elevation, for either communications or angle-tracking. The system includes two parabolic cylindrical reflectors, which are respectively a main reflector and a sub-reflector; the reflectors are positioned with the focal axes thereof orthogonally. A point or multibeam (e.g., monopulse) feed is mounted adjacent the main reflector on the focal axis of the sub-reflector in the Airy disc of the system. Beamwidth is controlled using telescoping sections on the main and sub-reflectors to control the size of the surface areas thereof. Simultaneous operation of the telescoping sections of the reflector and sub-reflector provides bidirectional zooming of the beam without distortion while individual operation of the sections of the reflectors permits unidirectional zooming. Bidirectional zooming of beams from the multibeam feed requires rotating the position of the multibeam feed as the Airy disc changes during adjustment of the telescoping sections.