A New Look at the Integral Equation Solution of High Frequency Diffraction Problems

In this paper we report a transform method for combining the integral equation and high frequency asymptotic techniques, e.g., the geometrical theory of diffraction or GTD. The method takes advantage of the fact that the Fourier transform of the unknown surface current distribution is proportional to the scattered far field. Two methods are developed for systematically improving the initial form of the high frequency asymptotic solution by manipulating the integral equation in the Fourier transform domain. Two salient features of the transform method are that it provides a convenient validity check of the solution and that it yields both the induced surface current density as well as the far field. Several illustrative examples that demonstrate the usefulness of the approach for handling a variety of electromagnetic scattering problems in the resonance region and above, and comparison with other methods are included in this paper.