Second-mode Spoof Surface Plasmon Polaritons Based on Complementary Plasmonic Metamaterials

In this paper, spoof surface plasmon polaritons (SSPPs) are supported by plasmonic metamaterial with arrays of complementary symmetric grooves. In comparison with the slotline-based complementary SSPP structure, the proposed structure has a different second-mode dispersion relation which indicates improved operating bandwidth. High-efficiency and broadband excitation and propagation of second-mode SSPPs are achieved by a smooth transition using a linear tapered coplanar waveguide with complementary gradient grooves. The transition is of seamless connection with conventional microwave circuits and simple geometry for easy and low-cost fabrication. The numerical simulations show that the proposed structure has significant potentials in developing plasmonic integrate circuits at microwave frequencies.