Measurement Method for the Dispersion Curves of a Spoof SPP Transmission Line Using a Single Sample

Research works on spoof surface plasmon polariton (SPP) transmission lines (TLs) have been carried out toward the goal of achieving flexible control of dispersion. The existing measurement methods for the dispersion of the spoof SPPs require two SPP TL samples with different numbers of units and transition structures, which makes the process more difficult and expensive. This work proposes a new approach for measuring the dispersion curve of a spoof SPP TL by using experimental near-field data. A mathematical model is presented to describe the relation between the wavenumber $k$ and the near-field data by considering the presence of reflected waves. The high efficiency and accuracy of this method are verified by the good agreement obtained between the measured dispersion curve and the eigenmode simulation result for a typical spoof SPP TL. Hence, the proposed method makes it possible to measure the dispersion curve of a spoof SPP TL based on a single sample, providing significant progress toward decreasing testing error and cost.