Spectral-domain analysis of electromagnetic scattering by periodically corrugated surfaces with local deformation

This paper considers the electromagnetic scattering from a periodically corrugated surface, in which the reference level is locally deformed, and presents a spectral-domain formulation based on the coordinate transformation method (C-method). The C-method is originally developed to analyze the plane-wave scattering from perfectly periodic structures, and based on the pseudo-periodicity of the fields. The fields in imperfectly periodic structures do not have the pseudo-periodic property and the conventional C-method is not applicable. This paper introduces the pseudo-periodic Fourier transform to convert the fields in imperfectly periodic structures to pseudo-periodic ones, and the C-method becomes then applicable.