A study on theory and physical mechanism of an infinitesimal current-carrying point charge

Abstract

Abstract-In antenna theory, the dipole hypothesis is applicable and widely used for observing the far-field radiation. However, when applied to near-field quasi-static radiation observation in geophysical surveying, the transceiver distance is often small, and thereby the source should not be treated as a dipole to avoid misfit between the observation and the modeling based on the dipole theory. To overcome such limitation, this paper first presents a new method of estimating the field generated from a dipole by dividing it into a series of infinitesimal point charge and computing both the velocity field excited by uniform-motion charge and accelerated-velocity field from accelerated charge, so that not only the far-field radiation but also the near-field quasi-static radiation can be accurately estimated. The results are well verified by the traditional methods of radiation modeling from a dipole. Then this study investigates the associated physical mechanism by developing a new equation for computing the radiated field in time-domain based on the frequency-to-time transformation, from which the relationship between a motive charge and its corresponding field is investigated. It is concluded that the field generated from dipole is in nature the same as that generated from motive charge.