Accurate Analyses of the On-Axis Fields of a Circular Disk by Transient and Harmonic Excitation

The computation of near zone fields is very important in many practical applications. Accurate analyses of the on-axis fields of a circular disk by transient and harmonic excitation show that there is an energy uprising zone on the axis rather than a non-decaying one, provided that the disk is excited by a rectangular pulse, the duration of which is less than the ratio of the radius to the light velocity. Similar results corresponding to the time-harmonic excitation are also given, which are quite different from the conclusions derived by Silver.