Dispersion curve of the helically corrugated waveguide based on helicoidal coordinate transform

Zhang, Liang and Easton, Jack and Donaldson, Craig R. and Whyte, Colin G. and Cross, Adrian W. (2022) Dispersion curve of the helically corrugated waveguide based on helicoidal coordinate transform. IEEE Transactions on Electron Devices, 69 (6). 3427 - 3432. ISSN 0018-9383 (https://doi.org/10.1109/TED.2022.3170279)

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Abstract

This article presents the dispersion curve study of the helically corrugated waveguide (HCW) using the 2-D finite element method (FEM) method based on the helicoidal coordinate transform. Calculation of the dispersion curve is 60 times faster compared with 3-D FEM simulation while maintaining similar accuracy. The 2-D method was used to investigate the relative error between it and a 1-D analytical method based on perturbation theory. Over a narrow parametric range, the 1-D method has a similar dispersion (within a relative error of 3%) in comparison to the 2-D/3-D methods but the error greatly increased when the parameter space was expanded. Correction factors were determined to greatly enhance the 1-D method accuracy over the wider parametric range. Assisted by the improved 1-D method, it allows identifying the desired operating mode automatically within the multiple eigenvalues from the 2-D simulation results. Therefore, it can be integrated into an optimization routine to explore the applications of the HCWs at wider parameter ranges.