Mush-Room Structures–Loaded Coplanar Waveguide Spoof Surface Plasmon Polariton with Reduced Longitudinal Length

A new coplanar waveguide (CPW) spoof surface plasmon polariton (SSPP) transmission line (TL) with mushroom structures is proposed. The analyses of the equivalent circuit reveal that the proposed SSPP requires shorter longitudinal length and also more compact size occupation than the conventional unloaded SSPP TL for achieving the same asymptotic frequency. Besides, the dispersion curve of the proposed SSPP can be controlled flexibly without changing the transversal geometric dimensions. To illustrate the design principle, a SSPP TL is designed, fabricated, and tested. It is validated that the utilization of mush-room structures is beneficial to the size reduction of the plasmonic devices.