A Reconfigurable Intelligent Surface for Arbitrary mm-Wave Polarization Using Parasitic Enhancing Structures

The design of a reconfigurable intelligent surface (RIS) for mm-waves with arbitrary polarization is proposed. At mm-wave frequencies, the RF switches needed in the RIS suffer from low isolation, and therefore a parasitic enhancing structure (PES) is also proposed to improve switch performance. In the RIS element, a dual-port dual-polarized patch antenna is used for scattering. Both ports of the antenna are connected to independent phase-reconfigurable circuits based on diodes, with PES, and these can provide 180-degree phase shifts. Simulation results show that the RIS can operate effectively for two orthogonal polarized waves and therefore an arbitrarily polarized wave.