Dual-PolarizedRIS-BasedSTBCTransmission withPolarizationCouplingAnalysis

The rapid development of the reconfigurable intelligent surface (RIS) technology has given rise to a new paradigm of wireless trans-mitters. At present, most research works on RIS-based transmitters focus on single-polarized RISs. In this paper, we propose a dual-polarized RIS-based transmitter, which realizes 4-transmit space-time block coding (STBC) transmission by properly partitioning RIS's unit cells and utilizing the degree of freedom of polarization. The proposed scheme is evaluated through a prototype system that utilizes a fabricated dual-polarized phase-adjustable RIS. In particular, the polarization coupling phenomenon in each unit cell of the employed dual-polarized RIS is modeled and analyzed. The experimental results are in good agreement with the theoretical modeling and analysis results, and an initial re-search effort is made on characterizing the polarization coupling property in the dual-polarized RIS.