Unified Theory of Characteristic Modes: Part II - Tracking, Losses, and FEM Evaluation

This is the second component of a two-part paper dealing with a unification of characteristic mode decomposition. This second part addresses modal tracking, interpolation, the role of ohmic losses, and presents several numerical examples for surface-based method-of-moment formulations. A new tracking algorithm based on algebraic properties of the transition matrix is developed, achieving excellent precision and requiring a very low number of frequency samples as compared to procedures previously reported in the literature. The transition matrix is further utilized to show that characteristic mode decomposition of lossy objects fails to deliver orthogonal far fields and to demonstrate how characteristic modes can be evaluated using the finite element method.