Surface Plasmonic Waveguide Developed from Glide Symmetric Dumbbell Grooves and Its Application in Microwave-Frequency Wideband Filters.

In this work, the degeneracy of the two lowest-order modes of spoof surface plasmon polariton (SSPP) is realized by the surface plasmonic waveguide (SPW), which takes the form of a slotline with glide symmetric dumbbell grooves. It is found that the non-zero group velocity can be observed on the two lowest-order modes at the Brillouin zone boundary of such glide symmetric SPW, which exhibits higher propagation constant of the dispersion relation than conventional non-glide SPW. The dispersion relation of SSPP unit cells when glide symmetric conditions are broken is also calculated and analyzed by the finite difference time domain (FDTD) method. Finally, a wideband bandpass filter (BPF) based on this glide symmetric waveguide scheme is designed for validating its broadband essential attribute and circuitry function. The experimental and simulation results show good consistency. The proposed glide symmetric SPW may be potential applications in plasmonic devices and wideband leaky-wave antenna at the microwave or THz frequency. [ABSTRACT FROM AUTHOR]