Multifunctional Dual-Band Energy Selective Surface Based on Two-Layer Diode-Loaded FSS

Abstract

<p>This article presents a multifunctional dual-band energy selective surface (ESS) based on a two-layer resonant circuit model with high-power microwave (HPM) protection ability for two bands. An equivalent circuit model (ECM) engineering multiple stopbands and passbands with combinations of parallel and serial resonators is proposed for dual-band design. By loading diodes in the resonator accordingly, the operating band can be switched from low insertion loss (IL) state to high shielding effectiveness (SE) state power-dependently. Additionally, the independence of two bands is greatly improved by utilizing two separate layers to mount the diodes, attributing to the enhanced difference of induced voltage between diodes in different layers resulting from shielding effect of top layer. Various functions in two-frequency co-incidence scenarios are analyzed, demonstrating the advantage of independent modulation. Based on the ECM, a two-layer ESS is designed. Two wide bands with IL<1dB under low-power incidence and SE>20dB under HPM are achieved, due to second-order resonance produced by double-layer configuration. The multiple nonlinear functions of the design are verified by field-circuit co-simulations. Several prototypes are measured, exhibiting 0.6&25.2 dB and 0.7&27.3 dB of IL&SE at two central operating frequencies for low-power and high-power incidences, respectively, with good agreement with the simulations. </p>