Liquid‐Crystal‐Based Reconfigurable Intelligent Surface for 7 GHz Mobile Communication

ABSTRACT Reconfigurable Intelligent Surfaces (RIS) offer a promising solution to mitigate signal blockages by dynamically shaping the wireless environment. Yet, large‐area deployment is still constrained by scalability, power consumption, and integration complexity. This paper introduces a Liquid Crystal‐based RIS optimized for the 7 GHz band, a critical frequency for beyond 5G (B5G) and emerging 6G technology, as it provides a favorable trade‐off between bandwidth and coverage. The proposed architecture integrates a differential coplanar waveguide phase shifter with a printed dipole antenna on a glass substrate, fabricated entirely by LCD‐compatible processes. A mirror‐balanced active‐matrix driving scheme enables analog phase control with sub‐0.1 W power consumption and high spatial resolution. The fabricated 4 × 5 LC‐RIS prototype demonstrates a maximum differential phase shift of 300° with only 12 Vpp driving voltage across a 7.2% phase‐shift bandwidth (6.65–7.15 GHz). Over‐the‐air evaluations in a complete 5G NR system, utilizing a custom greedy phase‐search algorithm, demonstrate signal‐to‐noise‐ratio gains of 3.23 dB and 5.30 dB under 1‐bit and 2‐bit phase quantization, respectively. These results establish LC‐based, AM‐driven glass panels as an energy‐efficient and manufacturing‐scalable materials platform for future transparent and reconfigurable wireless infrastructures.