Deep-Subwavelength Slot-Enhanced Broadband Dynamic Camouflage Metasurface Across the S, C, X, and Ku Bands

The rapid progress of microwave imaging technology has made conventional camouflage materials with fixed absorption performance ineffective. As the imaging band expands, camouflage materials capable of broadband operation, especially in the S and the C band, dynamic modulation are required to hide targets in complex environments. Here, we propose a dynamically modulated camouflage metasurface employing deep-subwavelength slots to enhance multiband modulation capability. By varying the vertical displacement of the structure, reflectivity can be modulated from below -10 dB to near 0 dB over 2.7-19.1 GHz (150.4% relative bandwidth), while maintaining insensitivity to the incidence angle and polarization. An equivalent interface-impedance model is established to reveal the mechanism of slot-enhanced low-frequency resonance. The laser processing parameters are optimized to reduce the slot width to 25 μm (λ _max/4440), enabling broadband dynamic modulation, as experimentally verified. Benefiting from its broadband dynamic modulation performance extending to the S and the C band, the proposed camouflage metasurface demonstrates potential for countering emerging microwave imaging technologies.