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 capacitive-coupled 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.