Source method for the evaluation of multipole fields

Abstract

Abstract The multipole expansion is an approximation technique useful whenever one wishes to obtain the electromagnetic fields far away from the sources. Here we present an alternative way to perform the multipole expansion which is more economic than usual treatments, specially in time-dependent situations. This method is based on a Taylor expansion directly on the sources (charge and current distributions), instead of the usually performed expansion on the fields. We apply this source method to calculate explicitly the complete fields of an arbitrary time dependent point magnetic dipole and point electric quadrupole.