Broadband high-order mode of spoof surface plasmon polaritons supported by compact complementary structure with high efficiency.

In this work, spoof surface plasmon polaritons (SSPPs) supported by microstrip lines with T-shaped complementary grooves are proposed. Compared with the traditional SSPP structure based on single-conductor transmission lines, a broadband high-order mode of SSPPs can be predicted from the dispersion diagrams. Besides, a decrease in transverse size of 75% can be realized under the same asymptotic frequency.