A Dual-Band Varactor-Tunable Frequency Selective Surface with Excellent Angular Stability

In this paper, a dual-band varactor-tunable bandpass frequency selective surface (FSS) with angular stability is proposed. The FSS comprises composite multi-resonance metallic structure where varactors are mounted symmetrically and bias network etched on the opposite side of the dielectric substrate, achieving dual passbands with independent tunability. Simulation results demonstrate that the proposed FSS exhibits continuous operating frequency from 2.4 to 5.75 GHz and from 5.7 to 9.63 GHz by controlling the bias voltage applied to the corresponding varactors. Moreover, it maintains angular stability for incident angles up to 75° under both TE and TM electromagnetic waves.