A Method of Moments Approach for the Simulation of Truncated RIS

A Method of Moments (MoM) approach for truncated Reflective Intelligent Surface (RIS) is proposed. The response of the truncated RIS is obtained as the sum of a term that includes only the grounded slab and a term with the response of the metallization on the same slab. The first term is truncated to the dimensions of the finite RIS based on a Physical Optics (PO) approximation. This approach is validated analytically and numerically in the case of a finite metallic plate on the grounded substrate. Besides, an analysis methodology for RIS made of printed parallel strips is developed assuming a structure infinite in one direction and is validated using a full 3D MoM code for a RIS finite in both directions.