Reconfigurable intelligent surface (RIS) has been widely considered as a key technique to improve spectral efficiency for 6G communications. Compared with most existing research that only focuses on the reflective RIS, the design and prototyping of a novel transmissive RIS are presented in this paper, and its enhancement to the RIS-aided communication system is experimentally demonstrated. The 2-bit transmissive RIS element utilizes the penetration structure, which combines a 1-bit current reversible dipole and a 90{\deg} digital phase shifter based on a quadrature hybrid coupler. A transmissive RIS prototype with 16×16 elements is designed, fabricated, and measured to verify the proposed design. The measured phase shift and insertion loss of the RIS element validate the 2-bit phase modulation capability. Being illuminated by a horn feed, the prototype achieves a maximum broadside gain of 22.0 dBi at 27 GHz, and the two-dimensional beamforming capability with scan angles up to ±60{\deg} is validated. The experimental results of the RIS-aided communication system verify that by introducing the extra gain and beam steering capability, the transmissive RIS is able to achieve a higher data rate, reduce the transmit power, improve the transmission capability through obstacles, and dynamically adapt to the signal propagation direction.
@article{arxiv.2206.15133,
title = {Transmissive RIS for 6G Communications: Design, Prototyping, and Experimental Demonstrations},
author = {Junwen Tang and Mingyao Cui and Shenheng Xu and Linglong Dai and Fan Yang and Maokun Li},
journal= {arXiv preprint arXiv:2206.15133},
year = {2022}
}
Comments
20 pages, 8 figures. This paper fabricates a 16$\times$16 transmissive RIS and develops a transmissive RIS-aided mmWave communication prototype to demonstrate its performance