Offset Dual-Reflector Antenna System Efficiency Predictions Including Subreflector Diffraction

A simple analytical formula for the prediction of diffraction efficiency in offset dual-reflector antenna systems is presented, and its performance evaluated by comparison to commercial software physical optics and method-of-moments simulations. The formula only requires knowledge of the symmetry plane physical configuration of the reflectors and an analytical approximation of the feed radiation pattern, and is therefore very straightforward to implement and use as a design aid. Some example applications of the formula are presented and discussed.