Broadband Achromatic Programmable Electromagnetic Camouflage via Fluidic-Accessible Metasurface

Broadband and reconfigurable illusion camouflage remains a major challenge in electromagnetic wave manipulation, as it imposes concurrent demands for precise dispersion control together with reliable real-time switching across wide frequency ranges. Existing metasurface cloaks typically suffer from narrow bandwidths and limited adaptability, rendering them unsuitable for dynamic radar detection scenarios. Herein, we propose and experimentally demonstrate a Fluidic-Accessible Metasurface (FAM) that overcomes these limitations by enabling programmable electromagnetic illusions through focal-spot encoding. The supercells are designed with strong dispersion control and achromatic focusing capabilities, thereby generating stable scattering hotspots from the radar perspective. Through the assembly and fluidic reconfiguration of these supercells, the FAM dynamically reconstructs the illusionary contours of diverse targets, such as aircraft, drones, and tanks, within an ultrawide operational bandwidth of 9-14 GHz. Experimental near-field measurements, in agreement with full-wave simulations, verify reliable and repeatable illusion camouflage states without leakage or degradation during fluidic reconfiguration. This strategy, therefore, unifies broadband operation, dynamic programmability, high adaptability, and structural robustness, directly addressing the key limitations of existing metasurface cloaks. This work establishes a versatile platform for programmable electromagnetic illusions, enabling the practical deployment of next-generation intelligent metasurface camouflage systems.