Active Reconfigurable Intelligent Surface Element for Bidirectional Polarization Enhancement

This work presents a novel active reconfigurable intelligent surface element, which can amplify full polarization incident wave and reconfigure reflection phases. The element consists of three discrete parts, such as scattering patch, reconfigurable phase shifters (RPSs), and reflection amplifier. The scattering patch decomposes the incident wave into two orthogonal components and reradiates them to space with enhanced amplitude and modified phase. RPS comprises four
$\boldsymbol{\pi}- \mathbf{type}$
resonators composed of inductors and varactors. By controlling the bias voltage of the varactor, the reflection phase of an element could be continuously adjusted. A class-E type reflection amplifier is employed to enhance the reflected waves with ultralow power consumption. The proposed element could be used for enhancing the full-polarization incident waves, which is of considerable significance in wireless communication applications such as Internet-of-Things, next-generation wireless communication networks, and spatial repeaters.