Phase Sensitivity Evaluation of Dual-Controlled Reconfigurable Intelligent Surface for Future 6G Communications

This study investigates the phase sensitivity of a dual-controlled reconfigurable intelligent surface (DC-RIS) when subjected to oblique illuminations. Unlike traditional RIS systems, the DC-RIS utilizes symmetry unit-cells and removes via-walls. Each component of the DC-RIS is regulated by a 2-bit varactor voltage at a maximum 10V. Simulation outcomes demonstrate that the phase sensitivity differs between horizontally polarized (HP) and vertically polarized (VP) waves. While keeping the azimuth angle (α) constant at 45°, the phase sensitivity for HP decreases as the elevation angle (β) rises, while the phase sensitivity for VP experiences a rapid increase. For β=60°, the phase sensitivity is computed at 47.6°/bit for HP and 83.3°/bit for VP. Moreover, recommendations are proposed to address the issue of angular instability.