An optically transparent metamaterial structure with simultaneously broadband microwave absorptivity and low infrared (IR) emissivity is proposed. Two specifically designed optically transparent metasurfaces were combined to realize radar and IR bi-stealth. One was designed to control the microwave absorption though properly modifying the impedance and resonance peaks of the meta-atom. The other was designed to control the IR radiation. Within a wide incident angle of ±60°, the proposed structure displays high absorptivity greater than 90% in the region of 6.28–12.29 GHz for TE polarization. For TM polarization, the absorptivity in the region of 7.19–15.26 GHz is greater than 90%. The IR emissivity of the metamaterial structure is about 0.30 in the IR region from 3 µ m to 14 µ m. The perfect consistency between experimental results and simulation results demonstrates that the proposal has practical application of multispectral stealth technology.

Optically transparent metamaterials with the performance of infrared radar compatible stealth have been designed and manufactured on the basis of the continuous in-depth research on single-band stealth technology. In this paper, metamaterials are designed through theoretical calculations and modeling simulations. The designed structure can achieve higher than 90% broadband (8.7-32 GHz) absorption at wide-angle (45 degrees), emissivity of 0.3 in infrared atmospheric window, and optical transparency. In addition, the material can be bent, which greatly expands its application scenarios. The experimental results are consistent with the theoretical calculation and simulation results.

A visible-light-transparent metasurface has been designed to achieve infrared (IR)–radar stealth. An optically transparent material, indium tin oxide was chosen in preference to other low-IR-emissivity metals to achieve camouflage compatibility for the IR–radar stealth material. In addition, flexible polyethylene terephthalate was adopted as the dielectric material to in order to benefit from its visible light transparency; its softness could also improve its application prospects. The fabricated structure exhibited a strong absorptivity of over 90% from 8.265 GHz to 17.65 GHz and a low IR emissivity of less than 0.3 in the region of 3–14 μ m. The results demonstrated that the metasurface was polarization independent and it was still able to maintain 90% of its absorptivity with an oblique incidence of 20°. The good consistency between the experimental and simulated results verified that the proposed metasurface can be practically applied in multifunctional stealth technology.

In this paper, a novel design of a co-polarized transmission window within the cross-polarized reflection band of a polarization converted meta-surface (PCM) is presented. First, a dual-band reflective polarization converted meta-surface is designed. In each band, the incoming linearly-polarized electromagnetic wave will be efficiently reflected with its cross-polarized state. The two bands are separated by a co-polarized reflective band. Second, a pass-band frequency selective surface (FSS) with the high-selective response is constructed. Its operating pass-band is positioned in the same range as the co-polarized reflective band of the PCM. Third, the reflected PCM without metal backing is integrated with the pass-band FSS, namely, a novel dual-band reflected PCM with a transmission window is realized. The -0.5dB-bandwidths of the two cross-polarized reflective bands are about 3.8 GHz (5.66~9.46GHz) and 2.0 GHz (16.9~18.9GHz), respectively. The -3-dB bandwidth of the transmission window is approximately 1.35 GHz (12.2~13.55 GHz). Lastly, the proposed structure prototype is fabricated and tested. The measured results are in good agreement with the simulated ones. In addition, the principle of operation and detailed design is also presented and discussed.

A broadband tunable metematerial absorber is proposed and demonstrated. As demonstrated in waveguide, the absorber consists of eight U-shaped ferrite particles and a metallic ground plane. These U-shaped ferrites directly act as resonators, and when the incident electromagnetic wave and applied magnetic field are simultaneously acting on the Ushaped ferrite particles, U-shaped ferrites can produce ferromagnetic resonance (FMR). Absorption frequency of the allferrite absorber can be tuned by the applied magnetic field and the saturation magnetization. Simulation results show absorption above 70% in the frequency range from 8.55 GHz to 10 GHz under applied magnetic field with 0 H =2700 Oe. By analysis, we find that the magnetic loss and dielectric loss lead to broadband absorption. The experiment test agrees well with the simulation results under different applied magnetic fields. This work provides an alternative route to realize tunable perfect absorbers with all-ferrite structures. With the artificial design of ferrite materials, the broadband tunable absorber can be designed and well serve in high power environment.