Systematic approach to control feed scattering and multiple reflections in symmetrical primary-fed reflector antennas

An improved method for accurately analysing symmetrical primary-fed reflector antennas is presented. The method, which is referred to as the multiple-scattering approach, takes into account the blockage caused by the feed in a very accurate way by also including the mutual coupling between the feed and the reflector. The coupling is treated as a multiple-scattering process. It is expressed in terms of the scattering pattern of the feed, which is the scattered field when the feed is excited by a plane wave with unity amplitude. To validate the method, a reflector antenna with a self-supported dipole-disk feed is investigated. The gain, the copolar sidelobes and the cross-polar level are much more accurately predicted by the multiple-scattering approach than by existing methods, provided that the scattering pattern of the feed can be determined with sufficient accuracy