A wideband, transparent and flexible microwave metamaterial absorber

As a new type of artificial composite material, metamaterials have attracted numerous attentions in the fields of physics, materials science and electromagnetics for its unique electromagnetic properties. A transparent and flexible metamaterial with wideband microwave absorption properties was proposed in this work. The reflection-type metamaterial was composed of a microwave absorption layer, a dielectric substrate and a reflective backplane. The impedance matching curves of the microwave absorption layer was deduced based on the impedance matching theory to improve the accuracy and efficiency of the wideband optimization design. Simulated results show that absorption higher than 90% can be achieved in the frequency band ranging from 8.2-22 GHz, corresponding to a total wideband of 13.8 GHz. The relative bandwidth reaches up to 91.4%, realizing wideband absorption while the thickness of the metamaterial is only 0.091 times the upper-cutoff wavelength. In addition, the metamaterial absorber is insensitive to polarization angle since its unit cell is symmetrical. Moreover, by rationally selecting materials of polyvinyl chloride (PVC) and indium tin oxide (ITO), the metamaterial absorber in this work is optically transparent and flexible, thus quite suitable for window radar stealth and equipment conformal stealth.