A Physical Optics Approach to the Analysis of Metascreens

Artificial screens based on metasurfaces (MTSs), also called metascreens (MetSs) are becoming a very popular tool for electromagnetic field manipulation. While significant research efforts have been devoted to the development of synthesis methodologies, less work has been done for the accurate modeling of real structures based on this concept. This paper presents a method based on a Physical Optics (PO) for the efficient description of the scattered field of metascreens consisting of a stack of MTS separated by dielectric layers. The derivation of the PO currents is based on the definition of proper transmisssion coefficients for the electric and magnetic fields which, in turn, relies on an equivalent transmission line model of the multilayer structure. In this model, the MTSs are represented through homogenized equivalent surface impedances. The proposed model takes into account the non-local transmission properties and the finite thickness and size of the MetS. The accuracy in the scattered field prediction has been verified through comparison with full-wave simulations.