An Ultra-Wideband 1-Bit Suspended Reconfigurable Intelligent Surface for Enhancing Wireless Coverage

This letter proposes an ultra-wideband 1-bit suspended reconfigurable intelligent surface (RIS) designed to enhance the signal coverage of wireless communication networks. The RIS unit cell comprises two metal gratings connected via a PIN diode, a dielectric-air-dielectric interlayer, and a metal reflective layer. The RIS achieves a stable reflection phase difference of 180° ± 30° between the ON and OFF states of the PIN diode within the ultra-wideband range of 2.75–6 GHz. This range includes the 3.4 GHz and 4.9 GHz bands for 5G communication, the 5.2 GHz band for indoor wireless communication, and the 5.8 GHz band for Wi-Fi and Bluetooth signals. A prototype, consisting of 20 × 20 unit cells, was fabricated and measured, demonstrating two-dimensional wide-angle beam scanning of ± 60° within the working frequency range. Furthermore, a RIS-assisted wireless communication system was constructed, confirming that deploying RIS can significantly enhance communication quality in targeted areas by transmitting and receiving image information at different frequencies. The proposed RIS holds substantial potential for RIS-assisted wireless communication systems.