Design and Prototyping of Wide-Band Transmissive RIS for Enhanced Wireless Communications

Reconfigurable intelligent surfaces (RISs) hold significant potential for enhancing coverage and data rates in 6G wireless communication systems. While most research has concentrated on reflective RIS applications, studies on transmissive RIS (TRIS) have been largely limited to simulations or laboratory prototypes. To evaluate the real-world performance of TRIS, we developed a 256 -unit cell, 1-bit TRIS prototype operating at the 5.8 GHz frequency band. The design employs an antisymmetric configuration of two PIN diodes, achieving nearly uniform transmission amplitude with inverse phase states over a wide 20 % bandwidth. The fabricated TRIS, composed of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$16 \times 16$</tex> unit cells, demonstrates effective 1-bit phase tuning with minimal insertion loss and a 3 dB transmission bandwidth exceeding 1.2 GHz. By dynamically modulating the quantized code distributions, we achieved scanning beams of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 60^{\circ}$</tex>. Subsequently, we integrated the TRIS into a Wi-Fi wireless communication system and assessed its performance in a real-world wall-penetration scenario. The TRIS improved the average Signal-to-Noise Ratio (SNR) by 8 dB, with a maximum gain of 15 dB, across a 29 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{m}^{2}$</tex> indoor area. Download speeds also increased, showing a maximum improvement of 10.57 Mbps and an average gain of 8.01 Mbps. These results highlight the effectiveness of TRIS in reducing path loss, enhancing SNR, and improving WiFi performance in challenging wall-penetration environments, ultimately leading to a better user experience.