Phase Sensitivity Study in Wide-Angle Incidences of Dual-Controlled Reconfigurable Intelligent Surface

This paper investigates the phase sensitivity and angular insensitivity of a dual-controlled reconfigurable intelligent surface (DC-RIS) under wide-angle illuminations. Utilizing CST simulations, the RIS is designed with polarization-symmetry unit-cells without via-walls and controlled by 2-bit varactor voltage in a range of 0-10V. The study reveals that the phase sensitivities for HP waves and VP waves are 51.2°/bit and 68.9°/bit, respectively, when $\boldsymbol{\beta}$ is fixed at 45°. Similarly, when $\boldsymbol{\alpha}$ is fixed at 45° and $\boldsymbol{\beta}$ is changed, the phase sensitivities are 50.3°/bit and 72.1°/bit. The phase sensitivity at normal incidence is 60°/bit. These results confirm the RIS's angular insensitivity and its potential for practical applications.