A unified approach to the characterization of frequency and polarization selective surfaces

A unified theoretical model describing frequency (and/or polarization) selective surfaces (FSS) is presented and discussed. Analysis of mixed multigrid structures, with both capacitive and inductive grids,is carried on by solving a global matrix system, without any limitations on the distance between the grids. Very complex structures can be analyzed by collapsing several grids together and by taking into account the metal thickness in the inductive grids. The problem of periodically holing the elements of both kinds of grids is handled in terms of equivalent modal circuits. Analysis and measurements relevant to a double ring structure are provided. An experimental validation of the theory has been performed by a measurement on a waveguide sample.<<ETX>>