Shaping of Dual Reflector Antennas for Improvement of Scan Performance

Modern communications satellites are equipped with high gain re­flector antennas with contoured beams for various purposes. A con­toured beam of complex cross section is generated by exciting several feed elements simultaneously, where each feed radiates a narrow and almost circular beam. The element beams which are di­rected towards the edge of the coverage region will suffer from various scan degradations.

For future systems there is a need for more frequency re-uses and improved beam coverage flexibility. Simultaneously there is a trend towards the use of higher frequencies, such as the 20/30 GHz bands. This will result in narrower element beams and the scan aberration is likely to be a limiting factor for the performance that can be realized.

The present paper describes a technique for shaping the reflector surfaces of a dual reflector antenna system. In this way a very significant reduction of the scan aberrations in a multibeam antenna may be achieved.
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Publication: Antennas and Propagation Society International Symposium, 1985