Meta‐atom design and communication prototype for wideband reconfigurable intelligent surface

Existing research on reconfigurable intelligent surfaces (RIS) has mainly focused on narrowband applications due to limitations in programmable metasurfaces and field prototype realization. This letter introduces a wideband RIS meta‐atom consisting of a single‐layer frequency selective surface supported by a dogbone‐shaped patch, ensuring a stable linear phase interval around the resonant frequency. A RIS communication prototype is constructed to evaluate its phase bandwidth upper limit and fundamental bandwidth properties. An equivalent circuit model is derived to predesign the wideband RIS meta‐atom, controlled by a varactor, and experimental validation in an anechoic chamber confirms its large bandwidth. Additionally, a wideband RIS‐assisted self‐contained prototype is demonstrated to illustrate the bandwidth characteristics and link gain enhancement at a system level. Test results indicate a researched bandwidth of up to 19.65%, with the 1‐bit RIS board achieving a 3‐dB gain bandwidth of about 8.62%.