Multimode equivalent circuit modelling of frequency selective surfaces

The authors extend the equivalent circuit approach by adopting a multimode network description for a plane wave arbitrarily incident on a metal strip grating at an air-dielectric interface. This formulation of the problem allows them to derive multimodal components for the equivalent circuits thereby increasing the accuracy of the models. The new static network is similar to that derived by Marcuvitz (1951) but an arbitrary number of higher modes can be included, with different dielectric media on each side of the frequency selective surface. Results are compared with experimental measurements and the usefulness of the approach is discussed