Efficient computation of generalized scattering matrix for analyzing multilayered periodic structures

An efficient technique is proposed for the computation of the generalized scattering matrix (GSM) of a dielectric interface with periodic metallizations. The technique is based on a spectral domain moment method, but assuming multiple incident Floquet-harmonics and computing the GSM directly. Also, some symmetry properties are exploited, and the whole GSM is computed with similar computer effort as that required for a single scattering coefficient. The technique has been applied to the analysis of periodic surfaces involving rectangular and arbitrarily-shaped metallizations using entire- and sub-domain basis functions, respectively. Losses in both dielectric layers and metallizations have been included in the formulation. Multilayered periodic structures are analyzed in a very flexible and efficient way by cascading iteratively the GSM of each interface with or without metallizations considered as building blocks. Numerical results have been provided for different multilayered structures, and a good agreement with other experimental and theoretical data has been obtained. The proposed technique is very appropriate for the analysis of composite structures when the separation between interfaces is small, and therefore higher-order Floquet-harmonic interaction cannot be neglected