Efficient propagation of spoof surface plasmon polaritons supported by substrate integrated waveguide with bandpass features

This paper presents an effective strategy that enables the efficient propagation of spoof surface plasmon polaritons (SSPPs) based on substrate integrated waveguides (SIWs). The dispersion property of SSPPs supported by a SIW-based unit cell is firstly analyzed and compared with that of traditional SSPPs. After which transmission characteristics of SSPPs as well as the corresponding field distributions are investigated to demonstrate the predicted bandpass features. Then, parametric analysis is performed to reveal the geometrical parameter effects on the passband. A smooth transition is designed for high-efficiency excitation based on quantitative extraction of dispersion property and impedance. A prototype of a SIW integrated with arrays of uniform holes on the top layer is fabricated and tested. The design is of simple geometry which enables easy and low-cost fabrication and overcomes the restriction of the limited depth of blind via hole. The measured results show that the upper and lower cut-off frequencies are in accordance with those in the dispersion diagram. Moreover, SSPPs can be inspired and propagated with very high efficiencies (return loss almost better than -10 dB) and good bandpass features (relative bandwidth as high as 93.9%), which validates the feasibility of the proposed strategy as well.