Volume Equivalence Principle

When the scatterer is magnetic, the magnetization phenomenon exists. There are two different models-magnetization electric current (MEC) and magnetization magnetic current (MMC)-used to depict the magnetization phenomenon. The volume equivalence principle based on the MEC model is simply reviewed. The volume equivalence principle based on the MMC model is proved rigorously. The difference between the MEC-based and MMC-based convolution integral formulations (CIFs) are clarified, and the advantages of the MMC model is emphasized. The MMC-based CIF derived in this paper is applicable to both "the scatterer placed in the free-space environment" and "the scatterer placed in the non-free-space environment". The MMC-based CIF is valuable for many numerical applications, such as the method of moments (MoM) and characteristic mode analysis (CMA) for scattering problem.