Multifunctional Reconfigurable Intelligent Surface for Wideband Beamforming and Frequency-and-Spatial-Diverse Microwave Sensing

Reconfigurable intelligent surface (RIS), known for their wave manipulation capabilities, are emerging as key technologies, especially in communication and sensing. In this article, we introduce a multifunctional RIS that is noteworthy for its substantial relative impedance bandwidth coverage of 41.3%, offering both frequency and spatial diversities for wideband wide-angle beamforming and object sensing. The proposed multifunctional RIS has been fabricated and measured. Moreover, the RIS utilizes wideband wide-angle beamforming and frequency-and-spatial-diverse technology to demonstrate dual functions: enhancing broadband wireless signals using quadrature amplitude modulation (QAM) and detecting passive objects. Regarding wireless signal enhancement, the RIS boosts signals by an average of 8 dB compared with a metal plate within the wideband frequency range of 15–21 GHz. In terms of frequency-and-spatial-diverse sensing, the proposed RIS is able to sense objects against a background. By introducing joint frequency and spatial diversity, the proposed RIS can further increase capacity in both wireless communication and sensing systems. The multiple functions make the RIS and highly relevant for sixth-generation (6G) communication systems and integrated sensing and communication (ISAC) applications.