An inexpensive scanning dual offset reflector antenna with rotating flat subreflector

Many communication applications, such as direct broadcasting by satellite (DBS) reception, require antennae with good scanning capability. The proposed dual reflector antenna system uses a single fixed feed, a shaped main reflector and a small flat subreflector which is rotated with respect to its central axis. Using only one feed, and hence only one amplifier front end, but moving only the small subreflector presents the least expensive scanning antenna alternative. Blockage in this dual reflector is minimized by choosing an offset configuration. A 30 wavelength illuminated diameter main reflector maintains excellent performance for all beams within a 20/spl deg/ field of view.