Computing Eigenvalues of Waveguides by a Modified Method of Auxiliary Sources

A modified method of auxiliary sources incorporating an excitation source is applied for computing the eigenvalues of hollow waveguides. Specifically, the eigenvalue determination is based on the response measurement of the waveguide’s domain to an excitation source. Theory and numerical results are presented proving that, contrary to external excitation, for internal excitation the eigenvalues are determined without a regularization procedure. The derived results are compared to those obtained with the Finite Element Method (FEM). We, also, discuss that divergent and oscillating auxiliary currents do not affect the eigenvalues’ determination.