On the usefulness of reciprocity in approximate scattering analyses

The use of reciprocity in estimating the accuracy of approximate scattering analyses is discussed. The physical optics and image induction approximations, valid for large smooth body scattering, are combined to demonstrate that approximate solutions satisfying reciprocity may not be any more accurate than nonreciprocal ones. The purpose of this communication is to point out that while it is certainly better, in general, to deal with approximate solutions which are reciprocal, it is not always possible to relate reciprocity and accuracy.