Configurations of dipoles, moving charges and currents for dynamic spherical multipoles

Abstract

Configurations of dipoles, moving point charges and current loops are presented for the dynamic spherical multipoles of the electric and magnetic type, whose fields are the vector spherical wave functions (VSWFs). The configurations produce the VSWFs of a specific degree and order in the limit that they become infinitely small. We find frequency independent configurations for up to degree $n=5$ or higher in some cases, which exceeds the current range of configurations in the literature for up to $n=3$, and our configurations for $n=3$ are simpler. We also investigate the link with anapoles and toroidal multipoles.