Dual‐Polarized Reflecting Intelligent Surface With Wide‐Angle Scanning for 6G Communication Relay

Abstract

This paper presents a dual‐polarized quasi‐2‐bit reflecting reconfigurable intelligent surface (RIS) for 6G communication relay applications. The reconfigurable reflective unit consists of two orthogonally placed printed dipoles with truncated corners and a circular patch. The circular patch introduces additional coupling capacitance to the dipoles, which not only reduces the unit's reflection loss but also broadens the operating bandwidth. Each dipole is loaded with a PIN diode to control the reflection phase. Two types of 1‐bit prephased reconfigurable units are designed by adjusting the relative length of the dipole arms, achieving quasi‐2‐bit quantization with a phase step of 90°. Taking the main lobe direction, sidelobe level, and gain roll‐off as the optimization objectives, a two‐stage genetic algorithm is adopted to optimize the prephase and phase distribution in the array. The simulation and test results for the 12 × 12 RIS array demonstrate that the array achieves a beam scanning range of ±60° with a gain roll‐off less than 3 dB in the frequency band of 6.5–7.5 GHz. The proposed design uses a single resonant substrate layer, with each polarization controlled by a single diode.