Optically Transparent Broadband Microwave Absorption Metamaterial By Standing‐Up Closed‐Ring Resonators

• Published in: Advanced optical materials 2017-07, Vol.5 (13), p.n/a
• Main Authors: Hu, Dawei, Cao, Jie, Li, Wei, Zhang, Cheng, Wu, Tianlong, Li, Qifan, Chen, Zhihong, Wang, Yilong, Guan, Jianguo
• Format: Article
• Language: English
• Subjects: Bandwidths; Broadband; broadband microwave absorption; Electrons; Graphite; Indium tin oxides; Magnetic resonance; Materials science; Mathematical analysis; metamaterial absorber; Metamaterials; Microwave absorbers; Microwave absorption; Nanoparticles; nonplanar metamaterials; Opacity; optical transparency; Optics; Polymethyl methacrylate; Resonators; Stacking; standing‐up metamaterials; Transmittance; Weapons
• ISSN: 2195-1071; 2195-1071
• DOI: 10.1002/adom.201700109

Optically transparent metamaterial microwave absorbers (MMAs) developed so far unexceptionally encounter an intrinsic contradiction between extending the absorption bandwidth and improving optical transparency, hindering their practical applications. This work, in its experiment and calculation, demonstrates an MMA with both broadband microwave absorption and excellent optical transparency by standing‐up closed‐ring resonators (CRRs) in an indium tin oxide backed Plexiglas board. The as‐designed MMA shows a strong microwave absorption of 85% covering a wide frequency of 5.5–19.7 and 22.5–27.5 GHz up to a large incident angle of 70o due to the electric and magnetic resonances caused by the standing‐up arrangement of the CRRs, as well as the multiple reflection mechanism. Moreover, in sharp contrast to the widely adopted stacking multiple layers at the expense of greatly reduced optical transparency, it has an optical transmittance of around 82%, as calculated by a transfer matrix method. The standing‐up MMA proposed here provides an effective way to achieve broadband microwave absorption and high compatibility with optical transparency, enabling wide applications in window glass of stealth armament and electromagnetic compatible buildings/facilities. An optically transparent metamaterial absorber, obtained by standing closed‐ring resonators in an indium tin oxide backed Plexiglas board, demonstrates both a bandwidth for 90% microwave absorption exceeding 14 GHz and an average optical transmittance of 82% due to the simultaneous excitement of electric and magnetic resonances, as well as the multiple reflections.