An Ultra-wideband Filter Using Spoof Surface Plasmon Polaritons Waveguide

This work presents an ultra-wideband bandpass filter based on spoof surface plasmon polaritons (SSPP) waveguide. The low-pass characteristic is achieved by SSPP waveguide that SSPPs unit consists of corrugated metallic strip with rectangular grooves. A vertical planar capacitor is placed in the center of the filter to couple the surface waves of SSPPs waveguides on both sides of the dielectric substrate, so as to introduce the high-pass characteristics. A design example is used to illustrate the method of ultra-wideband bandpass filter. The high and low cut-off frequencies can be controlled by the groove depth of SSPPs unit and planar capacitor. The simulated result shows the extremely wide -3dB bandwidth from 2GHz to 24GHz with -2 dB insertion loss. The proposed filter provides a potential ultra-wideband application in microwave and terahertz systems.