A network theory for EBG surfaces. Generalization to any direction of propagation in the azimuth plane

The generalization of the method presented in Maci et al. allows an efficient dispersion analysis for printed periodic FSS-type surfaces. The method, which has been tested here for a dipole-FSS backed by a ground plane, consists of a pre-processing performed on the broadband reflection-coefficient data obtained from a full-wave analysis. After that, the FSS is characterized via its resonances for a few values of the incident angles. This determines in a straightforward way poles and zeros of an equivalent impedance, simply synthesized by an L-C dispersive circuit. Due to the weak dispersion features of poles and zeros, the L-C circuit can be identified in a simple analytical form which, after analytical continuation, is applied to formulate the transverse resonance equation. The process is much simpler and faster than a full-wave solution for dispersion, while being sufficiently general.