Electromagnetic protection materials are widely used in both military and civilian fields. However, the limited wave-absorbing band and low transparency of conventional electromagnetic protection materials are the impediment for extensive applications. Here, a transparent and electrically tunable wave-absorbing metamaterial for stealth technology and electromagnetic protection has been theoretically and experimentally realized. The trend of the absorption feature change in simulation is consistent with that of the experiment results. The main part of this material adopts a sandwich structure consisting of two layers of indium tin oxide (ITO) and one layer of glass in between. The upper ITO layer is periodically patterned and combined with varactor diodes, which function as a frequency-selective surface. The effective operating frequency range is in the S-band, which covers the common frequency band of WiFi and many other electronic devices. The wave absorbing performance of this material can be electronically tunable by changing the applied voltage. The main absorption peak can be up to 90% with a tunable amplitude range of 30% and a tunable frequency band range of 1 GHz, and the transmittance of the sample in the visible is 80.23%. The metamaterial has high performance on electromagnetic shielding, whose effectiveness is larger than 30 dB in the range of 2.6–3.95 GHz. This transparent and tunable metamaterial has great potential for the applications in electromagnetic protection and stealth.

A transparent and tunable metamaterial absorber with simultaneously low infrared (IR) emissivity is proposed in this Letter. The designed structure consists of an infrared shielding layer (IRSL), a radar absorber layer (RAL), and an air/water dielectric layer with an indium-tin-oxide (ITO) backplane. Both the IRSL and RAL are made of ITO films and polyethylene terephthalate substrates, so the absorber exhibits optical transparency. By changing the thickness of the water layer, the 90% absorption band can be converted from 7.6–12.5 to 12.8–18.2 GHz. The absorber is polarization insensitive and stable at wide incidence angles. The IR emission value of IRSL is 0.24. Both numerical simulations and experimental measurements demonstrated the good performance of the proposed structure, indicating its great potential applications in multi-spectrum compatible stealth.

An optically transparent chessboard metasurface is proposed to achieve wideband radar cross section (RCS) reduction in this paper. The metasurface is a single-layer sandwich structure composed of indium-tin-oxide (ITO) square patches with different sizes and surface resistances, polyethylene terephthalate (PET) substrate, and ITO backplane from the top downwards. Based on optimized multielement phase cancellation (OMEPC) to select the sizes and surface resistances of ITO patches, the proposed metasurface can achieve the 10 dB RCS reduction from 10.1 to 26.4 GHz with a relative bandwidth of 89% under normal incidence. The total thickness of the metasurface is 2 mm, which makes it highly flexible. When there is a slight cylindrical curvature on the metasurface and the curvature angle is less than 30°, an approximate 10 dB RCS reduction can still be achieved in the frequency range of 10-25 GHz under normal incidence. When the oblique incidence angle is less than 45°, the proposed metasurface also exhibits nearly 10 dB RCS reduction at the specular direction in the frequency range of 10-25 GHz. Finally, a sample is fabricated and measured, and the experimental results are in good agreement with the simulation results.

This paper studies the radar cross section (RCS) of carrier electronic warfare airplanes. Under the typical naval operations section, the mathematical model of the radar wave’s pitch angle incidence range analysis is established. Based on the CATIA software, considering dynamic deflections of duck wing leading edge flaps, flaperons, horizontal tail, and rudder, as well as aircraft with air-to-air missile, anti-radiation missile, electronic jamming pod, and other weapons, the 3D models of carrier electronic warfare airplanes Model A and Model B with weapons were established. Based on the physical optics method and the equivalent electromagnetic flow method, by the use of the RCSAnsys software, the characteristics of carrier electronic warfare airplanes’ RCS under steady and dynamic flights were simulated under the UHF, X, and S radar bands. This paper researches the detection probability of aircraft by radars under the condition of electronic warfare, and completes the mathematical statistical analysis of the simulation results. The results show that: The Model A of carrier electronic warfare airplane is better than Model B on stealth performance and on discover probability by radar detection effectively

This paper proposed a single-layer checkerboard metasurface with simultaneous wideband radar cross-section (RCS) reduction characteristics and low infrared (IR) emissivity. The metasurface consists of an indium tin oxide (ITO)-patterned film, a polyethylene terephthalate (PET) substrate and an ITO backplane from the top downwards, with a total ultra-thin thickness of 1.6 mm. This design also allows the metasurface to have good optical transparency and flexibility. Based on phase cancellation and absorption, the metasurface can achieve a wideband RCS reduction of 10 dB from 10.6 to 19.4 GHz under normal incidence. When the metasurface is slightly cylindrically curved, an RCS reduction of approximately 10 dB can still be achieved from 11 to 19 GHz. The polarization and angular stability of the metasurface have also been verified. The filling rate of the top ITO-patterned film is 0.81, which makes the metasurface have a low theoretical IR emissivity of 0.24. Both simulation and experimental results have verified the excellent characteristics of the proposed checkerboard metasurface, demonstrating its great potential application in radar–IR bi-stealth.