Numerical Computation of Dispersion Curves in Arbitrary Cylindrical Metal SWSs Without Approximating the Boundary Shape With Fourier Series Expansion

Traditional numerical method of calculating the dispersion curves of arbitrary slow wave structures (SWSs) is to use Fourier series expansion to represent the radius function r(z) of the SWSs. This method is inconvenient for we have to try several times to choose proper numbers of Fourier series to approximate the boundary function well and to achieve high numerical accuracy of the dispersion curves simultaneously. In this paper, we derive and solve a universal dispersion equation of the symmetric and asymmetric modes in arbitrary SWSs without using Fourier series expansion to approximate the boundary function.