Double Notch Spoof Surface Plasmon Polaritons Filter Based on Double-layer Hybrid Substrate Integrated Waveguide

In this paper, the bandpass response is constructed by combining the highpass characteristics of SIW structure and the lowpass characteristics of Spoof Surface Plasmon Polaritons (SSPP) structure. Two notches in the passband are realized by introducing another layer of substrate and two pairs of open-loop resonators. The measurement results show that the passband range of the filter is $8.5 \mathrm{GHz} \sim 11.8 \mathrm{GHz}$, the two notches are located at 10.56 GHz and 11.26 GHz with notch depths of $\mathbf{- 1 6 . 9 2 \mathrm { dB }}$ and $\mathbf{- 2 1 . 6 4} \mathrm{dB}$ respectively. The measurement results are consistent with the simulation ones, which puts forward a new idea for the design of notch filters based on SIW-SSPP hybrid structure.