Focal region fields of three dimensional Gregorian system

Maslov’s method is applied to derive high frequency field expressions for the wave reflected by a three dimensional Gregorian system when the plane wave is incident. Expression is relatively simple and is valid in the caustic region. Geometrical optics approximation generally used to study high frequency field, fails in the vicinity of a caustic. Maslov’s method is a systematic procedure for predicting the field in the caustic region combining the simplicity of ray and generality of the transform method. Field distributions around the caustic region are calculated and the results are compared with obtained using current distribution method. Agreement among them is fairly good.