Dispersion properties of periodic grounded structures via equivalent network synthesis

The increasing interest on metamaterials and frequency band-gap structures has been motivated by the large number of recently discovered engineering applications in the field of microwaves and antennas. A method is presented for the efficient dispersion analysis (associated to both surface-waves and leaky-waves) for printed periodic FSS-type surfaces. The method has been tested for a gangbuster FSS backed by a ground plane. Preprocessing is 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 angle. 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 dispersivity of poles and zeros parameters, 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 resulting process is much simpler and faster than a full-wave solution for dispersion and provides an accurate initial guess for the iterative identification of the leaky- and surface-wave solutions.