Hi Array,nI tried but the overall structure simulated in driven mode, as shown in the attached figure [1], is different from the target structure in eigenmode. The reason is that the mode I want to study/use cannot be excited efficiently using plane waves. The waveguide section and the transition in between the waveguide and the target structure are used to physically and efficiently excite the mode. As a result, due to the existence of discontinuity, I could not deembed to get a pure dispersion relation of the target structure from driven mode solution data, which is the motivation of me doing the eigenmode analysis.nnThank you.n[1] Q. L. Zhang, B. J. Chen, K. F. Chan and C. H. Chan, High-Gain Millimeter-Wave Antennas Based on Spoof Surface Plasmon Polaritons, in IEEE Transactions on Antennas and Propagation, vol. 68, no. 6, pp. 4320-4331, June 2020, doi: 10.1109/TAP.2020.2970122.n