Spectral-domain approach to electromagnetic scattering from imperfectly periodic structures

A spectral-domain approach to the electromagnetic scattering from imperfectly periodic structures is shown based on the pseudo-periodic Fourier transform. The fields in imperfectly periodic structures have continuous spectra in the wavenumber space, and the main problem of the spectral-domain approach is the discretization scheme on the wavenumber. The present approach introduces the pseudo-periodic Fourier transform, which makes us possible to apply the conventional grating theory to the problems of imperfectly periodic structures.