A digital beam-forming multiple-beam reflector antenna subsystem for GEO communication satellites

This paper reports on the development of a multiple-beam reflector antenna subsystem applied for geosynchronous earth orbit (GEO) communication satellites. The subsystem is composed of two Gregorian reflector antennas, one operating in Ka band for uplink connections and the other in K band for downlink path. Each antenna consists of a large scaled feed array to provide the capability of wide angle coverage. The feed array is fed by a switch matrix which choses a part of feed elements to contact with TR channels at a time. Four independent beams are synthesized using digital beamforming techniques. With feed elements switched on and off by switch matrix, beams can scan in the coverage zone. A demonstrator of this antenna subsystem is recently fabricated and measured at the institute. Experimental results are presented in the context.