FSS-Based Fully Reconfigurable Rasorber With Enhanced Absorption Bandwidth and Simplified Bias Network

In this article, a fully reconfigurable frequency selective rasorber (FR-FSR) is presented. To establish systematic design guidelines, initially the conditions for full reconfigurability are derived. Then, a specific equivalent circuit model (ECM) is proposed which satisfies all the derived conditions. The circuit model is separately simulated to verify the proposed concept and further extensively analyzed to provide an in-depth design methodology for all three modes of operation. The ECM is further synthesized into a simple planar structure to obtain the design of the rasorber. In the proposed rasorber, both layers are independently reconfigurable with p-i-n diodes embedded in the top layer and varactors in the bottom layer, all symmetrically mounted to achieve polarization insensitivity. P-i-n and varactor diodes are seperately operated to achieve the desired mode of operation with minimum insertion loss. A simple and efficient bias network is proposed in such a way that it does not affect the performance of the rasorber. The sample prototype is also fabricated and experimentally tested where a good agreement between simulated and measured result is obtained.