Transparent and electrically tunable electromagnetic wave absorbing metamaterial

Abstract

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.

Visible–Infrared Transparent Ultra-Thin Frequency-Tunable Microwave Absorber Based on a Nanometer-Thick Patterned VO2 Film

“…In addition, based on the small duty cycle of the patterned VO 2 film and the metallic mesh, FTMAPV can achieve optical transparency in the visible–infrared band. Compared with the previously reported transparent tunable absorbers, ,,,, our designed FTMAPV has the thinnest relative thickness and the widest optical transparency wavelength range. The proposed absorber prototype is a viable solution for ultra-thin frequency-tunable microwave absorbers with broadband optical transparency and has numerous potential applications in optical and intelligent fields.…”

Metamaterial Absorbers: From Tunable Surface to Structural Transformation

“…By placing varactor diode between a gap in the resonator or the adjacent resonators (Figure 4a-e), the equivalent capacitance among periodic patterns varies, which results in shift of resonant frequency and change in absorption bandwidth. [62,102,105,[112][113][114] For example, a tunable MA with varactor diodes connected to two identical resonators is shown in Figure 4f. [62] Due to the capacitance changes of the varactor diode under reverse bias voltage (−19 V), the resonant frequency of the fabricated MAs increased from 4.35 to 5.85 GHz, exhibiting a W RTR of 29.4%, as shown in Figure 4g.…”

Block Building Architecture for a Multifunctional Broadband Electromagnetic Wave Absorber Based on the Freestanding Resistive Film

“…Wideband electromagnetic (EM) wave absorbers are essential in the EM wave shielding and stealth technology. − Because of the demands in stealth applications, wideband absorbers with light weight, trim sizes, and easy fabrication processes have drawn much attention recently. − Two standard absorber configurations, a multilayer structure , and lumped-element loaded design, − are often used to construct wideband absorbers. However, a multilayer configuration results in a bulky absorber, unsuitable for applications where miniaturization is of concern.…”