Optically transparent and flexible broadband microwave metamaterial absorber with sandwich structure

With the aim to design broadband microwave absorbers with optically transparent, flexible and stable performances in 8–18 GHz, a sandwich structure is designed and fabricated by sandwiching the periodic arrayed ITO film into two transparent and flexible polyvinyl chloride layers. With the induced metamaterial structure to tailor the effective input impedance, the proposed sandwich absorber can realize more than 90% absorption in 8–18 GHz for both TE and TM polarization when the incident angle is less than 30°. Meanwhile, the optical transmittance of the designed absorber reaches more than 80% transmittance with the wavelength larger than 532 nm, and the average optical transmittance for the visible light (400–800 nm) is 80.2%. The proposed absorber shows broadband microwave absorption in both X and Ku band with simultaneously high transmittance in visible frequencies, indicating that the proposed sandwich metamaterial absorber has great potentials for developing optical transparent absorbing devices.