Novel 1-bit hybrid reconfigurable intelligent surface.

Reconfigurable intelligent surfaces (RISs) are anticipated to play a key role in future smart wireless networks by enabling control over the propagation environment and improving communication performance. However, most existing RIS designs rely on external channel information acquisition, thereby restricting their autonomy. By embedding sensing directly into the RIS, the resulting hybrid RIS (HRIS) can pave the way for a self-configuring wireless network. However, previous HRISs used complex geometries, resulting in low sensing signal strength or costly implementation. This paper proposes a novel 1-bit HRIS designed to sense the incident signal's angle of arrival (AoA) and redirect it toward desired directions. This device consists of independently tunable resonant patch elements loaded with PIN diodes. To introduce sensing capabilities, a portion of the incident signal on each element is coupled into a parallel-plate waveguide (PPWG) via small rectangular slots. This PPWG is below the reconfigurable patch array of the HRIS and collects the coupled signal from all elements. Two coaxial connectors are then used to sample the signal coupled to the PPWG. We use computational processing and a multilayer perceptron (MLP) to analyze signals collected in this manner to detect AoA. Further, pre-coded phase randomization is implemented by varying slot sizes to suppress undesired quantization lobes. The proposed HRIS is simple and low-cost, and it can pave the way for intelligent wireless communication, power transfer, and sensing without requiring feedback loops.