An Advanced Eigenvector-Correlation-Based Tracking Method for Characteristic Modes

An advanced characteristic mode tracking method is investigated in this article. The tracking method is based on the eigenvector correlation, and a novel tracking error correction algorithm (TECA) is proposed to solve the challenging issues caused by the mode swapping and the mode degeneracy. As the core of the modal tracking method, the TECA can quickly find out the cross-mode pairs according to the eigenvalue differences among different modes, identify the wrongly mapped modes using the eigenvector correlation, and finally correct all the possible tracking errors. The detailed process of each step is described and discussed. In addition, the characteristic modes of two classical fractal antenna structures are investigated for validation. It has been shown that the modes including the swapped modes and degenerated modes are all tracked correctly, verifying the modal tracking method is reliable and efficient. Compared with the previous approaches, the proposed method is not subject to the number of tracked modes and the magnitude of eigenvalue. Also, it requires less computational time. Moreover, the sensitivity to the sizes of frequency step and mesh is reduced to some extent.