Differential microstrip lines with reduced crosstalk and common mode effect based on spoof surface plasmon polaritons.

We apply the concept of spoof surface plasmon polaritons (SPPs) to the design of differential microstrip lines by introducing periodic subwavelength corrugations on their edges. The dispersion relation and field distribution of those lines are analyzed numerically. And then through designing practical coupling circuits, we found that compared with conventional differential microstrip lines, the electromagnetic field can be strongly confined inside the grooves of the corrugated microstrip lines, so the crosstalk between the differential pair and the adjacent microstrip lines is greatly reduced, and the conversion from the differential signal to the common mode signal can also be effectively suppressed.