Sliding metasurface for wide-angle beam steering with sharp frequency filtering

The advancement of electromagnetic technologies necessitates strategies to efficiently exploit spectral and spatial resources in increasingly congested and interference-prone environments. This paper demonstrates, for the first time, a fully passive sliding metasurface that unifies sharp frequency filtering and wide-angle beam steering within a single architecture, thereby establishing a two-dimensional frequency-angle selection window. The proposed metasurface replaces local phase reconfiguration with a global geometric displacement between two complementary phase profiles. This sliding strategy produces a controlled translation of the spectral centroid in reciprocal space, enabling continuous beam steering and suggesting extensibility to other frequency regimes. In the demonstrated implementation, a transmission-line-inspired design is adopted, in which stacked layers are strategically reused to form a quasi-Fabry-Pérot cavity within the meta-atom, enabling simultaneous phase modulation and frequency-selective filtering. Experimental results validate sharp spectral selectivity, ultra-wide out-of-band suppression, and stable beam steering over a ± 57° scanning range. The proposed sliding metasurface offers a compact and broadly applicable platform for next-generation electromagnetic systems, enabling a new modality for coordinated spectral-spatial wave control.