A Wideband 1-Bit Reconfigurable Intelligent Surface with Polarization Conversion

This paper presents a novel wideband 1-bit reconfigurable intelligent surface (RIS) with polarization conversion for radar cross-section (RCS) reduction. The proposed unit cell is designed to convert the vertical polarization to horizontal polarization and vice versa in the operating frequency band. Indeed, to achieve polarization conversion, we integrate two PIN diodes as control elements with the resonant patch. Besides, only one PIN diode is turned “ON” at one time to provide one reflection phase value. The simulation results show that the proposed unit cell can convert the x-polarized to y-polarized EM wave and vice versa, with 180° (±10°) phase change over an ultra-wideband of around 2.91 GHz, equivalent to 26.45% fractional bandwidth. Furthermore, we have built and simulated a $12\times 12$ unit cell RIS to validate the beam steering ability. By simulation, we prove that the RIS with the proposed unit cell can convert the linear polarization as well as form a beam toward a desired direction with a proper reflection phase configuration set.