An Ultrawideband, Wide-Angle, and Transparent Microwave Absorber Using Indium Tin Oxide Conductive Films

In this letter, a microwave metamaterial absorber (MMA) with visible-light transparency, ultra- wideband, and wide incidence angle properties is proposed. The MMA is composed of two different materials with Indium Tin Oxide (ITO) conductive films and transparent polymethyl methacrylate (PMMA) substrate layers. And 90% absorption band from 2.5 GHz to 21.3 GHz with fractional bandwidth 158% is achieved by full wave simulation. Besides, the proposed MMA has high angular stability. When a transverse electrical (TE) mode with the oblique angles from 0${}^{\circ}$to 50${}^{\circ}$is incident, a perfect absorption above 90% has been achieved. And a similar phenomenon arises for the transverse magnetic (TM) mode from 0${}^{\circ}$to 70${}^{\circ}$. In accordance with the simulation, a sample with a size of 200×200 mm was fabricated. The experimental results agree well with the simulation, which verifies the feasibility of the design. The transmittance of the MMA in the visible wavelength range (400-750 nm) was also measured. The average transmittance can reach 62.05%. Thus, this design is expected to have potential applications in the fields of transparent microwave absorption and multi-spectrum stealth.