Array fed dual reflector synthesis for multiple beams

Requirements for antennas to provide multiple or scanned beams over a limited angular sector, are encountered in both satellite and radar applications. In such cases the hybrid antenna, consisting of one or two reflectors illuminated by a small phased array, can provide a cost effective and flexible solution. The authors describe a new synthesis method for such configurations, which allows all of the design requirements to be addressed. The technique is quite general, but has initially been implemented in two dimensions, where scanning is considered only in the offset plane of the reflectors. The synthesis of a single beam antenna is described. This forms the basis of an iterative procedure for the synthesis of the multiple beam systems. Four design examples are considered, covering cases where the power distribution over the main reflector aperture may be equal to, or different to that over the feed array