Dual-band multiple beam antenna system for communication satellites

摘要

A dual-band multiple beam antenna system for a communications satellite sharing a set of reflector antennas for the transmit and receive frequencies. One set of reflectors is common to both the downlink and uplink frequencies. The feed horns are diplexed and exhibit frequency-dependent radiation patterns that separate the phase centers over the downlink and uplink frequency bands to obtain dual-band performance. The focal point of the reflector is in close proximity to the phase center corresponding to the downlink frequency band. The phase center for the uplink frequency band is spaced a predetermined distance from the phase center of the downlink frequency band. According to the present invention, the uplink frequencies are defocused and the downlink frequencies are focused thereby creating identical radiation patterns at both frequency bands and over the coverage region of the communications satellite.