Subspace-Based Inverse Source Method for Fast Synthesis of Large-Scale RIS With Advanced Power Pattern Shaping

This communication aims to facilitate the design of large-scale reconfigurable intelligent surfaces (RISs) with the objective of achieving a specified advanced power scattering pattern. Specifically, the problem is formulated as finding a solution in the feasible equivalent source space that radiates fields closest to the desired far-field power pattern. To tackle this problem, an iterative projection method (IPM) is used. In the projection process from the far-field pattern to the equivalent source space, the introduced alternating projection operation (APO) is investigated, and its influence on the final synthesis results is discussed. The proposed method offers the advantages of being less time-consuming and flexible regulation, making it particularly suitable for large-scale RIS synthesis.