Energy Functionals and Variational Principle in Electromagnetic Modal Analysis—Part V: Re-exploring Magneto-Dielectric CMA

An important theoretical question—how to formulate a physically reasonable characteristic mode (CM)generating operator—on the characteristic mode analysis (CMA) for magneto-dielectric scatterers is re-explored, and the corresponding conclusion obtained previously is further reconfirmed by using some new methods different from the previous methods. The new methods are based on variational principle, work-energy theorem, and reciprocity theorem, and the new methods lead to the same conclusion as the one obtained previously. The conclusion is that: the CM-generating operator for magneto-dielectric scatterers should be formulated as the complex driving power done by the externally incident field on the scattered currents; during the process to formulate the CM-generating operator, the complex conjugate operations should act on the scattered currents (if do not act on the incident fields), or act on the incident fields (if do not act on the scattered currents).