Design and Modeling of Spoof Surface Plasmon Modes-Based Microwave Slow-Wave Transmission Line

This paper presents a theoretical model and validates experimentally the microwave slow-wave transmission line (SW-TL) based on spoof surface plasmon (SSP) modes. Equivalent circuit models are first presented for characterizing the SSP structures and developed to serve as an insightful guideline to design the SW-TL at a given cutoff frequency and Bloch impedance. A mode converter connecting a conventional microstrip transmission line to the SW-TL is necessarily proposed to ensure that the quasi-TEM modes of the microstrip line are gradually transformed to the operating TM modes of the SW-TL. The presented schematic of SW-TL paves a promising avenue for the unprecedented interconnector footprint miniaturization of integrated circuits, and the enhanced electromagnetic compatibility, for example, in multilayered monolithic microwave integrated circuits.