Analyzing multilayer FSS with the mutual admittance and spectral approaches

Frequency Selective Surface (FSS) is popularly applied as an electromagnetic filter. Frequency response of a perfect FSS should remain unchanged even if the angle of incidence and polarization vary dramatically. Sometimes, the transmission curve of specific FSS is designed to decrease quickly when it is not in band-pass range. It is difficult for single FSS to achieve the goal. Fortunately, multilayer FSS can be used in this situation. In the paper, the mutual admittance and spectral approaches are used to analyze multilayer FSS. Compared with other methods, these approaches have the characteristics of quick convergence and little computational time.