Improved dual-polarized wideband multifunctional switchable absorber/reflector based on active frequency selective surfaces

Abstract

An improved dual-polarized multifunctional switchable absorber/reflector with both wideband absorbing and wideband reflecting characteristics is presented in this paper. The proposed structure consists of three parts including a top-layer active frequency selective surface (AFSS) structure, a bottom-layer metal sheet and an air spacer in between. The polarization stability is satisfied by deploying the super-element topology, which contains four similar unitary elements arranged in a 2 × 2 matrix form. The PIN diode is employed as a RF switch in the AFSS structure for the purpose of switching. The bias networks responsible for different polarizations are intentionally separated through via holes. Multifunctional properties with four different operating states can be attained by controlling horizontally- and vertically-loaded PIN diodes independently. In addition, the biggest advantage of the proposed structure lies in its wideband features at both absorbing and reflecting states for different polarizations and incident angles. Finally, a prototype of the design is fabricated and measured to verify the simulation, and a good agreement between the simulated and observational results can be achieved under normal incidence as well as oblique incidence.