Design of 2-Bit Single Linearly Polarized Reconfigurable Intelligent Surface for Single-Beam/Multibeam Scanning

Single-beam/multibeam scanning is a key technology in modern wireless communications, where extensive works have been devoted to improving the performance of devices, such as the coverage capability. In this letter, a 2-bit single-polarization reconfigurable intelligent surface (RIS) for single-beam and multibeam radiation in the far field is proposed. Two diodes are loaded onto a trapezoidal patch, utilizing a four-layer printed circuit board (PCB) structure to construct independent control of 2-bit phase discretization, easy to manufacture. To enlarge the beam scanning range of the RIS, the cell period is designed as 0.41λ. Each p-i-n diode is independently controlled by the field-programmable gate array (FPGA), enabling real-time 2-D beam scanning. For demonstration, the prototype of the RIS is fabricated and measured, which is formed of 16 × 16 units and operates at 3.5 GHz. The far-field radiation patterns corresponding to single-beam and multibeam radiation are measured in the microwave chamber and the scanning beams with range of ±60° are also measured. In the direction of
θ
= 0°,
ϕ
= 0 °, the RIS has a gain as high as 21.3 dBi, the sidelobe level is less than −11 dB, and the cross polarization is lower than −30 dB.