Study on Convergence Stability of Iterative Method Applied to High-Frequency Electromagnetic Field Analysis

A high-frequency electromagnetic field analysis based on the finite element method is known for poor convergence of iterative methods. Furthermore, false convergence may occur in which a physically correct solution cannot be obtained even though the convergence criteria are met. In this paper, we show that false convergence occurs in a high-frequency electromagnetic field analysis based on the finite element method. We propose and compare two methods to avoid false convergence that are currently executable: lowering the convergence judgment value of the residual norm of the conjugate orthogonal conjugate gradient method and increasing the wavelength resolution.