Experimental Verification of Liquid Crystal-Based Reconfigurable Intelligent Surface for 6G Communications

Experimental verification of liquid crystal (LC)-based reconfigurable intelligent surface (RIS) for 6G communications is presented. Two different types of LC-based RIS unit cells are proposed and the beamforming performance of the fabricated 7×7 array prototype is analyzed. In the fabrication, LC mixture GT7-29001 from Merck KGaA is used to obtain a wide variation range of dielectric constant with low loss characteristics. The measured phase difference of the fabricated RIS prototype is more than 240° within the 1 GHz bandwidth (9.5-10.5 GHz). To verify the beamforming performance, the bias voltage configurations of the fabricated prototype to focus the beam in the 30° and 45° directions were analyzed. The measured S21 values at 10 GHz are increased by 11.1 dB and 7.7 dB for 30° and 45° beamforming, respectively.