Scattering of arbitrarily polarised, arbitrarily directed incident plane waves by frequency-selective surfaces

A planar frequency-selective screen (FSS) is considered in the presence of an arbitrarily polarised plane wave incident in an arbitrary direction. It is shown that the complex scattering coefficients for the parallel-polarised and the orthogonalpolarised components can be determined in terms of the principal-plane-incidence parallel-polarised values of the coefficients.