A Multi-layer Tunable Frequency Selective Surface with Highly Selective Response Based on Varactor Diodes

This article presents a highly selective Tunable Frequency Selective Surface (TFSS) based on varactor diodes. The multi-layer structure generates multiple resonance frequencies and transmission poles to suppressing the passage of out-of-band electromagnetic waves. In addition, it is used to improve the roll-off characteristics of TFSS. The simulation results show that TFSS can be resistively tuned between 10.33 and 11.12 GHz with a insertion loss between 0.17 and 0.03dB. The select characteristic relative bandwidth of multi-layer TFSS is T1 = 5.2% and T2 = 4.97%. Compared with the single-layer FSS, the proposed TFSS is increased by 84.4% and 83.6%, which verified the effectiveness of this method.