A Wideband Multifunctional Absorber/Reflector with Polarization-Insensitive Performance

A wideband and polarization-insensitive absorber/reflector with multifunctional characteristics is proposed in this paper. The designed structure comprises a switchable layer, an air spacer and a metal ground. The switchable layer contains active resonant elements, whose switching properties are realized by controlling PIN diodes. Bias networks for the PIN diodes are integrated into the structures and no dedicated bias lines are required. Thus, the negative effect of extra bias lines can be alleviated. In order to achieve switchable and polarization-insensitive properties simultaneously, a super-element configuration is developed by combining four similar unitary elements. One unique feature of the designed device lies in its real-time and multifunctional capability to switch among multiple working states. In addition, the switchable bandwidth of the proposed structure covers a much wider frequency band compared to previous switchable absorber/reflector designs. Distributions of electric field and surface current as well as an equivalent circuit model are presented to gain the necessary physical insight into the working mechanism of the switchable structure. Finally, a prototype of the proposed design is fabricated and measured for validation.