Optically Transparent Meta-Window with Radiative Cooling and Dual-Band Signal Enhancement

Windows account for a significant portion of the building energy loss. Conventional low-emissivity (low-E) glass, despite its efficacy in reducing infrared radiation for thermal insulation, fails to dissipate solar heat, resulting in a deteriorated cooling performance during summer. Besides, modern architectural environments demand not only efficient thermal regulation but also enhanced wireless communication performance across multiple frequency bands. In this paper, we propose a multifunctional metasurface window (meta-window) that simultaneously achieves dual-frequency microwave signal enhancement, passive radiative cooling, and high visible transparency. By utilizing multiresonance gridded meta-atoms and multilayer films, the meta-window effectively combines low-frequency microwave hybrid phase modulation with broadband high-frequency spectrum regulation. Experimental results show that for the dual-band microwave signal, the transparent metasurface effectively steers incident waves to designated signal blind zones while simultaneously achieving significant signal enhancement. For the purpose of thermal regulation, the meta-window demonstrates substantial indoor temperature reductions when compared to normal and low-E glazing, featuring high reflectivity in the near-infrared range and broadband high emissivity for mid-infrared waves. This strategy highlights promising applications for next-generation multifunctional windows by offering significant improvements in energy efficiency and signal reliability.