Multifixed-beam satellite antenna with full area coverage and a rain-tolerant polarization distribution

Two problems of multifixed-beam satellite antennas have been 1) gaps in coverage in a given field of view, and 2) use of polarizations which are sensitive to cross coupling caused by precipitation in the earth´s atmosphere. These problems can be solved, and in addition, large frequency reuse can be achieved, by application of cluster feeds to an offset Cassegrainian antenna. New features described here include a) interleaving of cluster feeds, b) use of linear orthogonal polarizations distributed to lie in local vertical and local horizontal planes on the earth´s surface, c) clusters of keystone-shaped feed elements, d) a system for interconnecting uplink and downlink beams, and e) a method for evaluating aberration-sensitive antenna parameters. It is found that aberrations are negligible for beams aimed within the contiguous United States.