Compact Bandpass Filter Based on Hybrid Spoof Surface Plasmon and Substrate Integrated Waveguide Transmission Line

In this paper, spoof surface plasmon polariton (SSPPs) and substrate integrated waveguide (SIW) based bandpass filter is proposed. The metal strip on the top of the substrate is composed of periodic slots which supports surface wave mode of SPP within the closed substrate integrated waveguide. The dispersion relation of the proposed structure shows that it has both low-pass feature of SSP and the high-pass feature of SIW, and hence the combination of these two features leads to a bandpass filter (BPF). The results show that the passband is from 11.5-19 GHz with relative bandwidth of 49%. Bandwidth can be controlled by properly adjusting the parameters of the design. The proposed design features a compact size and easy fabrication, due to the integration of SPP in a closed SIW.