Transformations of the Multipole Response Fields D and H for Magnetic Media

Abstract

Multipole theory for the response fields D and H in dielectrics yields unphysical (origin dependent) results when taken beyond electric dipole order. In view of the inherent non-uniqueness of D and H, we therefore consider transformations of these fields. For magnetic media, and to electric quadrupole-magnetic dipole order, we present a transformation, which restores the required origin independence. It also restores a constraint, first identified by Post, without affecting other necessary properties (symmetries). This approach can be extended to higher multipole orders.