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

TL;DR

This paper introduces a novel modal tracking algorithm based on algebraic properties of the transition matrix, improving precision and efficiency in characteristic mode analysis, especially for lossy objects, with applications to FEM evaluation.

Contribution

It presents a new algebraic transition matrix-based tracking algorithm and demonstrates characteristic mode analysis for lossy objects using finite element methods.

Findings

The new tracking algorithm requires fewer frequency samples.

Characteristic modes of lossy objects do not produce orthogonal far fields.

FEM can be used to evaluate characteristic modes of lossy structures.

Abstract

This is the second component of a two-part paper dealing with a unification of characteristic mode decomposition. This second part addresses modal tracking and losses and presents several numerical examples for both surface- and volume-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.