Ambient-energy-driven space-time-coding metasurface for space-frequency-division multiplexing wireless communications

• • Achieved four-channel space-frequency-division multiplexing with independent real-time image transmission to four user terminals, demonstrating a fourfold capacity increase over single-channel programmable metasurfaces without additional spectrum. • • Energy consumption per bit is remarkably low, enabling self-powered operation solely from ambient solar energy harvesting, eliminating reliance on external power supplies and reducing operational costs for dense network deployments. • • The shared-aperture design integrates solar cells and programmable elements on a single platform, achieving a compact form factor that facilitates flexible deployment in energy-constrained environments such as IoT devices and remote base stations. • • Experimental validation confirms low inter-channel interference and independent control of multiple frequencies and spatial directions, ensuring reliable multiuser communication with minimal signal degradation.