Frequency Selective Characteristic Based on Coupled Spoof Surface Plasmon Polaritons

We studied the two kinds of coupled mode of spoof surface plasmon polaritons (SPP), which are capacitivecoupled parallel mode and capacitive-coupled series mode respectively. Capacitive-coupled parallel SPP is composed of two oppositely oriented single-side corrugated strips coupled to two double-side corrugated strips, behaving as a wideband-pass filter. The slot between single-side corrugated strip and double-side corrugated strip can be considered as capacitance. Every two H-shaped unit cells used in capacitive-coupled parallel mode are regarded as a new unit cell as to capacitive-coupled series mode. And every two new unit cells are separated by a gap with certain distance along transmission direction. The slot between the new unit cells can also be equivalent to a capacitance. This kind of coupled mode will bring band-stop characteristic to the propagation of SPP. The models of the two kinds of coupled mode SPP were designed and verified the ownership of the corresponding frequency selective characteristic.