Design of 3-Bit Angle-insensitive RIS for 5G Communication Systems

This paper introduces a 3-bit reconfigurable intelligent surface (RIS) design characterized by its unique angle-insensitive properties for 5G communication systems. The proposed configuration provides eight distinct phase states enabled by the states of two varactors with an applied bias voltage. The design of the unit cell with double centric square split ring resonators and the formation of the RIS with a 5x5 array have been presented. A detailed analysis of the RIS performance has been conducted using the CST 3D electromagnetic simulator to study the reflection amplitude and phase responses. It is demonstrated that the results show a phase range of up to 315 degrees, along with eight distinct states exhibiting a stable interval of 45 degrees. This effectively covers incidence angles ranging from 0 to 60 degrees.