Optically Transparent Ultra-broadband Metamaterial Absorber

In this paper, two-layer periodically arranged water cylinders backed by the ITO film is developed to achieve optically transparent, ultra-broadband absorption, insensitive polarization, and wide incident angle simultaneously. The simulated results show an absorption efficiency larger than 90% in both the absorption bands of 4.6-33.7 GHz and 51-83 GHz. Furthermore, the proposed water-based MA has a wide-angle absorption performance for both TE and TM waves. It is interesting that the absorption performance is better and better with the increase of incident angle when a TM polarized plane wave is incident. Since the total thickness of the proposed MA is only 6.4 mm, it may have potential applications in the window of stealth equipment and electromagnetic compatible construction.