An optically transparent metamaterial structure with broadband microwave absorptivity is proposed. A specifically designed optically transparent metasurfaces was designed to control the microwave absorption though properly modifying the impedance and resonance peaks of the meta-atom. Within a wide incident angle of ±60o, the proposed structure displays high absorptivity greater than 90% in the region of 33.7-44.7GHz for TE polarization. For TM polarization, the absorptivity in the region of 11.8-37.2GHz is greater than 90%. The perfect consistency between experimental results and simulation results demonstrates that the proposal has practical application of multispectral stealth technology.
In recent years, the research on radar and infrared compatible stealth has attracted much attention. In this paper, metamaterials are designed by means of theoretical calculation and modeling simulation. The entire structure consists of an infrared shielding layer (IRSL), a radar absorbing layer (RAL) and a backplane. The simulation results show that when the angle between the incident microwave and the normal of the metamaterial is in the range of 0-40°, the average absorption rate of the structure in the 7-27 GHz band is relatively stable and reaches more than 90%. In the infrared band, the emissivity of the structure is lower than 0.28 and 0.32 at 3-5 μm and 8-14 μm, respectively. In addition, through the rational design of structure and materials, the metamaterial not only achieves dual stealth functions of low infrared emission and broad microwave absorption, but also has high transparency and flexibility, providing a new method for the study of multi-band stealth materials.
Infrared (IR) camouflage, which is used to conceal objects in infrared vision for confrontation with infrared detection in civilian and military applications, is gathered interest increasingly. Here, the tunable selective emitter depended on temperature is proposed. When the temperature is below 341K, the emitter has low emissivity in 3-5μm and 8-14μm, and high emissivity in 5-8μm. The bandwidth with the emissivity above 50% is 3μm; With the temperature above 341K, the average emissivity in 3-14μm is 0.23, which can achieve excellent infrared camouflage. The maximum modulation depth of emissivity is 51.56%. It is believed that the emitter can explore further applications in thermal management, adaptive thermal camouflage and energy harvesting.
In this paper, we proposed an infrared absorber based on multilayer film. Through the thickness resonance of ZnS dielectric layers and the loss properties of ultra-thin titanium film, a good absorption is achieved in the infrared band. The outermost ZnS is employed to reduce impedance mismatch and protects ultra-thin Ti film. This sample does not need inplane microstructure design, which reduces the processing difficulty and can be prepared on large scales.
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