James Randall Curtis

US Patent:

42740983, Jun 16, 1981

Filed:

Mar 7, 1980

Appl. No.:

6/128343

Inventors:

Jacques Renau - Culver City CA
James W. Curtis - Riverside CA
Donald S. Nicholson - Los Angeles CA
Frank L. Hennessey - Los Angeles CA

Assignee:

The United States of America as represented by the Secretary of the Air
Force - Washington DC

International Classification:

H01Q 1919

US Classification:

343781CA

Abstract:

A system for, and a method of, scanning a collimated beam of electromagnetic radiation with a very large primary reflector of an antenna system without loss (i. e. , with zero phase error) and without moving the primary reflector. The system is a two dimensional scan, loss-free, Cassegrain antenna system which comprises a stationary, parabolic-shaped, primary reflector, and a smaller, movable, parabolic-shaped subreflector, and also a movable, plane wave, electromagnetic radiation beam source interposed between the two reflectors. It is shown that, without moving the primary reflector, the beam can be scanned over wide angles with no phase error in the plane of scan, provided that the source and the subreflector are rotated about the focal point of the antenna in a specific manner. A unique angular relationship between the source and the subreflector is required for each scan angle, and is taught. The method includes the step of using this antenna system in scanning the beam from the primary reflector, without any phase error and without moving the primary reflector.