A Compact Rejection Filter based on Spoof Surface Plasmon Polartions and Folded Split-Ring Resonators with Controllable Rejection Bandwidth

摘要

A novel rejection filter composed of the single comb-shaped spoof surface plasmon polariton (SSPP) and the folded split-ring resonators (FSRR) is proposed in this letter. By embedding the FSRRs into grooves of the low-pass SSPP filter, the compact rejection filter with the same size as the low-pass filter is consequently realized. Compared with traditional ones, the proposed filter provides simpler structure, more compact size, lower insertion loss, higher frequency and controllable rejection bandwidth. The dispersion interprets the transmission modes of the rejection SSPP unit. And the approaches of controlling the rejection band prove the fine controllability in the filter. The fabricated filter has a size of 3.23/lambda(g)x0.24/lambda(g), a central rejection frequency of 18.43 GHz, a fractional rejection bandwidth of 7.8%, maximum rejection depth of 42 dB, and an average passband insertion loss of 2.5 dB. The simulated rejection bandwidth controllable range is 4.0%similar to 6.8%. Improved performances confirm the advantages of the proposed filter.