Fast implementation of characteristic mode tracking

Characteristic mode (CM) theory provides a physical and intuitive guidance for discussing electromagnetic radiating or scattering issues and is a useful tool for the antenna design. The effective mode sorting is the key to the CM analysis. However, due to the mode degeneration or mode swapping in the observed frequency range, the mode tracking must be performed to obtain the correct mode sorting. Current mode tracking algorithms are mainly based on the correlation of eigenvectors, but they are computationally expensive and time-consuming. Here, the eigenvector number is limited by selecting the eigenvalues, to speed up the tracking realisation. At the same time, the factors affecting the correctness of the mode tracking are discussed, including the selected eigenvalue number and the mesh fineness. Some numerical examples are given to verify the reliability of the improved algorithm.