Advanced 30/20 GHz multiple beam antenna for future communications satellites

A multiple offset reflector system is being used to provide multiple fixed and scanning beams at 30 GHz by means of a polarization grid diplexer to separate two orthogonally polarized feed assemblies. Each feed assembly consists of multiple fixed and scanning beam feeds. The technology developments required for successful operation of this proposed system are presented. These technologies include: (1) an offset Cassegrain system for low sidelobe wide angle scan beams; (2) a diplexed beam forming network for overlapping low sidelobe beams; (3) a fast switching network for scanning beams; and (4) fabrication of precision feed components and large offset reflectors.