Shaped subreflector for offset Gregorian reflector antenna with a paraboloidal main reflector

Abstract

The shaped dual offset reflector antenna configuration is considered to yield the best radiation pattern performance for FSS ground stations operating in a small angle satellite spacing environment, where the present trend is a continuous tightening of off-axis radiation levels specifications. When properly designed and fitted with a low cross-polarization primary feed, the shaped dual offset reflector antenna radiation pattern can easily meet the present ITU-R recommendation, achieving simultaneously high aperture efficiencies, above 90%, and low levels for the cross-polarization peaks in the azimuth radiation pattern plane. However, widespread utilization of this configuration is still curbed by the higher manufacture costs. In this paper, the possibility of reducing the manufacture costs for the dual offset configuration is explored by utilizing the parabolic offset reflector as the main reflector, and shaping only the subreflector. This solution can be very cost reduction effective, particularly for manufacturers that already have a highly diversified production of single offset antennas. Selected reflectors could then be easily utilized as the main reflector in a dual offset design fitted with a suitably shaped subreflector.