Sensing and Reconfigurable Reflection of Electromagnetic Waves from a Metasurface with Sparse Sensing Elements

Abstract

Reconfigurable reflective surfaces can form prescribed radiation patterns given a known incident signal, a capability with widespread use for beamforming in radar and imaging systems or for altering the propagation environment in wireless communication networks. For reflective surfaces to operate intelligently, they need to acquire the relevant information about the incident and reflection directions autonomously. Toward this goal, we design a metasurface that can generate reconfigurable radiation patterns as well as perform compressive sensing of the incident signals, allowing it to adapt its response without requiring feedback loops or dedicated links to transmitters or receivers-paving the way for autonomous and smart operation. To realize such an operation, we propose a metasurface consisting of two types of elements, conventional and hybrid. While both elements are designed to reflect the signal, the hybrid ones allow coupling of a small portion of the incident signal into a sensing layer. To ensure low loss and complexity, the number of hybrid elements and the associated sensing circuitry need to be kept small, which can degrade sensing performance. To circumvent this issue, we develop a compressive sensing scheme that leverages the inherent multiplexing of information within the metasurface's substrate to retrieve relevant information using a few sensing RF chains, thus guaranteeing low cost and complexity. As an illustrative example, we numerically demonstrate the possibility to detect angles of arrivals of single and multiple incident beams using full-wave simulations of the proposed structure. We also show that the proposed metasurface can form desired radiation patterns and the introduction of the sensing capabilities has a minimal impact on its main functionality. The proposed smart reconfigurable surface with sensing capabilities may operate autonomously and can benefit wireless communication, wireless power transfer, and imaging systems.