Physical Modeling of Reconfigurable Intelligent Surface for Channel Modeling

In this paper, a physical model of RIS of bistatic polarized radar cross section is derived starting from the Stratton-Chu equations under the assumptions of physical optics, PEC, far field and rectangular RIS element. In the context of important physical characteristics of the backscattering polarization of RIS, the modeling of the RIS wireless channel requires a tradeoff between complexity and accuracy, as well as usability and simplicity. For channel modeling of RIS systems, RIS is modelled as multi-equivalent virtual base stations (BSs) induced by multi polarized electromagnetic waves from different incident directions. The comparison between test and simulation results demonstrates that the proposed algorithm effectively captures the key characteristics of the general RIS element polarization physical model and provides accurate results.