Ultrawideband Optically Transparent Metmaterial Absorber

In this paper, an optically transparent, wide-angle, polarization-insensitive ultra-wideband metamaterial absorber is presented. The structure is a two-layer configuration. The unit cell of the first layer is composed of an indium tin oxide (ITO) film cross and a square ring, and that of the second layer is also a square ITO film ring with different size from the one on the first layer. Moreover, there is a complete ITO film on the back of the absorber which is used as the reflecting layer. Absorptivity of the structure is higher than 90% from 5.3 to 17.45 GHz, and the fractional bandwidth of the absorber is 106.8%. In addition, the structure is insensitive to polarization and incidence angle.