Broadband Propagation of High-order Mode of Spoof Surface Plasmon Polaritons Supported by Compact Complementary Structure

Abstract

In this work, high-order mode of spoof surface plasmon polaritons (SSPPs) with a broadband feature is supported by compact complementary structure. The proposed structure is constructed by microstrip lines with T-shaped complementary grooves, which can realize a decrease in transverse size of 75% in comparison with the rectangular grooves. More importantly, the operating bandwidth of high-order mode of SSPPs is greatly improved. Then a smooth and simple transition with gradient grooves is proposed to realize high-efficiency excitation of high-order mode of SSPPs and seamless connections between SSPP structure and microstrip lines. Based on the proposed transition, an SSPP waveguide is designed and simulated. The numerical results validate efficient excitation and broadband propagation (up to 12.1 GHz) of high-order mode of SSPPs. This work can find significant potential applications in designing high-performance antennas at microwave frequencies.