Fast Eigenmode Mapping in Printed Periodic Structures

We use the Method of Moments to study the isofrequency dispersion curve of conducting patches of general shape printed on a grounded dielectric substrate. To accelerate the method, we use a specialized interpolation technique to rapidly evaluate the periodic impedance matrix of the system for many different phase shifts between consecutive unit cells. The interpolation procedure is based on the extraction of an easy-to-compute rapidly varying term and the interpolation of the smooth remainder. Using the proposed method, computing the periodic impedance matrix for a new phase shift is a matter of milliseconds without sacrificing the accuracy. To validate the method, we reproduced results that are available in the literature.