Differential transmission lines with surface plasmon polaritons at low frequencies

A new kind of differential microstrip lines by introducing periodic subwavelength corrugation in the edge, which is able to support low-frequency spoof surface plasmon polaritions, is proposed. The surface current distribution of the subwavelength periodic corrugated microstrip is numerically analysed. A kind of differential to single-ended microstrip coupling circuit is designed to investigate the ability of suppressing the crosstalk of such a subwavelength periodic corrugated differential pair. Experimental results show that such a structure can be utilised to effectively suppress crosstalk, and to reduce the transformation between differential-mode and common-mode signals.