Ultra-wideband optically transparent radar-absorbing composite metastructure with embedded multilayer frequency selective surfaces.

Existing transparent metamaterial absorbers (MMAs) encounter a persistent challenge in reconciling low-frequency wideband radar-absorbing with high optically transparency. This study develops a multi-objective genetic algorithm integrated with a refined hexagonal electromagnetic model based on skewed periodic boundaries, incorporating the constraints of the bandwidth and total thickness of the optically transparent radar-absorbing composite metastructures (OTRACM). A 3D-printed framework-assisted resin infusion method is proposed for OTRACM, featuring functional units composed of embedded multilayer quartz glass thin plates pasted with patterned indium tin oxide (ITO) hexagonal ring patterned frequency selective surfaces (PFSS). The optimized OTRACM achieves reflectivity below -10 dB across 2.3∼18 GHz with 72.33% visible-light transmittance, while its effective absorption bandwidth covers S, C, and X bands for target detection and the Ku band for terminal guidance. Moreover, OTRACM exhibits exceptional multi-angle stability in its radar-absorbing performance, maintaining strong absorption for both TE and TM polarizations at incidence angles up to 45°. Owing to its superior integrated performance, OTRACM exhibits promising application potential in military stealth technology, electromagnetic information security, and protection of civilian electronic devices.