Fast Analysis of Metasurfaces Through Temporal Coupled-Mode Theory

In this article, a rigorous temporal coupled-mode theory (CMT) formalism is developed, to analyze metasurface (MTS)-based structures. Such MTSs are generally rather complex, requiring extensive, full-wave simulations. To facilitate their design and minimize the associated computational demand, the CMT solves a small linear system of equations, fed by the results of certain much simpler and less time- and memory-consuming eigenvalue problems. The proposed method is versatile and offers an initial, valuable estimation of the structure's frequency response, which may be used as a guideline for the final MTS fine tuning. As proof of concept, split-ring resonator (SRR) MTSs coupled to microstrip lines are analyzed, and their response is compared with the full-wave finite-element method (FEM) results.