Array fed multiple beam array reflector antenna systems and method

摘要

Array fed multiple beam antenna systems and methods for use on an orbiting spacecraft carrying a communication system. The antenna systems include a reflector and a relatively small array feed compared to the reflector. The array feed has feeds (radiators) that illuminate the reflector and that are disposed in a focal plane of the reflector. A power division network excites the radiators of the feeds. The antenna system is capable of very wide scan angle operation and may be used to provide multiple spot beam coverage over the surface of the Earth viewed from a synchronous orbit spacecraft. Phase aberration normally associated with scanning is corrected by adjusting excitation coefficients of each array feed. The spot beams are scanned across a field of regard by controlling the position of each feed in the focal plane and using the appropriate amplitude and phase distribution associated with a particular spot beam (array feed). The amplitude and phase distributions may be fixed or varied during operation. A dual band system includes a second array feed and a frequency selective surface disposed between the array feeds that optimizes the respective array feeds. Use of the frequency selective surface in dual band implementations produces a very efficient communication system.