Electromagnetic Scattering from Imperfectly Periodic Surfaces

This paper considers the two-dimensional electromagnetic scattering problem of periodically corrugated surfaces in which structural periodicity is locally collapsed, and presents a spectral-domain formulation based on the pseudo-periodic Fourier transform (PPFT). This transform converts an arbitrary function into pseudo-periodic one and the scattering problem from imperfectly periodic structure becomes possible to be formulated by the conventional grating theory. The present formulation uses the coordinate transformation method as the grating theory. PPFT introduce a transform parameter that relates to the wave number and the transformed function has a periodic property in terms of the parameter. The discretization scheme required in the spectral-domain approach can be considered only inside the Brillouin zone owing to this periodicity.