A spectral domain interpretation of high frequency diffraction phenomena

A spectral domain interpretation of high frequency diffraction phenomena is discussed using the concept of a spectral diffraction coefficient, which resembles Keller's coefficients. The solution of the two-dimensional problems of diffraction of an arbitrary field (with no caustics) by a half-plane is investigated and results are given for any observation angle including, in particular, asymptotic determination of the field at the shadow boundaries. The high frequency scalar diffraction by apertures is formulated in a systematic manner and the formulation, which is valid for any observation angle, is compared with that of other techniques. Results are also given for the diffracted field at the caustics.