A switchable and tunable multifunctional absorber/reflector with polarization-insensitive features

A switchable and tunable multifunctional absorber/reflector with polarization-insensitive performance is designed. The proposed structure comprises a switchable screen on the top layer, a tunable screen on the bottom layer and an air spacer in between. PIN diodes are employed in the switchable structure to provide multiple switchable states (dual-polarized absorber, dual-polarized reflector, TE/TM wave absorber/reflector and TM/TE wave absorber reflector) by actively controlling the feeding modes between “11” and “00” states. Tunable capability, are instead guaranteed by the tunable screen loaded with varactor diodes. The polarization insensitivity is guaranteed by constructing a super element, which is a combination of four similar unitary elements. To mitigate the adverse influence of the dedicated feed lines, independent coplanar and back feeding modes are configured to provide biases for PIN diodes and varactor diodes, respectively. Finally, a prototype of the proposed structure is fabricated and measured in a microwave anechoic chamber, and the measured results demonstrate both the switchable and tunable characteristics of the proposed multifunctional absorber/reflector.