Transform approach to electromagnetic scattering

In this paper, we present a comprehensive review of the Fourier transform technique as applied to the problem of high-frequency scattering and introduce the concepts of the spectral theory of diffraction (STD). In contrast to the more commonly employed ray-optical method for high-frequency scattering, viz. the geometrical theory of diffraction (GTD), the STD approach interprets the scattered field as the spectrum, or the Fourier transform of the induced current on the scatterer. Such an interpretation offers several important advantages: uniform nature of representation, capacity to improve and extend the ray-optical formulas in a systematic manner, and convenient accuracy tests for the results. Methods for combining integral equation methods with the Galerkin procedure and asymptotic techniques in the transform domain are described, and representative examples illustrating the application of the spectral approach are included.