Liquid-based transparent, wideband and reconfigurable absorber/reflector.

In this paper, an optically transparent and wideband absorber/reflector with switchable states and tunable frequency spectrum is presented. The proposed structure consists of a Polydimethylsiloxane (PDMS) layer with microchannel structures and an Indium Tin Oxide (ITO) layer as the metal panel. The switching function is implemented by controlling the injection and discharge of pure water, and the switchable frequency band of the absorbing and reflecting states ranges from 7.9 to 34.4 GHz with a fractional bandwidth of 125.2%. The tunable properties are achieved by changing the concentration of the injected saline water. In addition, the distributions of the electric field, the magnetic field and the power loss density are used to further understand the physical mechanism of the structure. Moreover, it also performs well under different polarizations and incident angles. For validation, a transparent and wideband absorber/reflector is fabricated and tested, and the simulated and measured results are consistent with each other.

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

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.