Multifrequency, High-Power, Cassegrainian Antenna Feed Systems for Satellite Ground Stations

The era of space communications has imposed new requirements on ground communications antenna design. The antenna feed system must provide the capability for high-power transmission and reception of signals for communications and tracking. The design of a Cassegrainian antenna configuration, which is being used in a satellite communications ground terminal, is discussed. The feed configuration is located at the vertex of a 30-foot parabolic reflector. It consists of a single transmitting feed located in the center of a cluster of four receiving feeds. The Cassegrainian design readily permits interchanging of feeds and subreflectors for operation at receiver frequencies which may vary by more than four to one without changing the pattern crossover level for tracking. A single feed configuration for operation with the Telstar and Relay satellites has been developed. It is now being used for communications experiments with the Telstar satellite.