Dual-passband independently controllable active FSS

A design method for the dual-passband independently controllable active frequency selective selective surface (AFSS) is proposed and implemented. Based on the equivalent circuit model (ECM) constructed by the design idea, dual-passband characteristics are obtained on a single layer using a multi-resonance structure. In order to achieve a wide passband and excellent in-band and out-of-band characteristics, a cascaded hybrid structure is used to construct the FSS, which produces two second-order passbands. Designed AFSS achieve the function of tunable low-frequency passband and maintained high-frequency passband, with the tunable low-frequency passband ranging from 3.31 GHz to 6.87 GHz, and the high-frequency passband basically maintained at $14.9 \mathrm{GHz}-18.5 \mathrm{GHz}$, and the insertion loss is less than -1dB.