Current Distribution and Radiation Properties of a Shunt-Excited Antenna

The shunt-excited antenna, first described and experimented with by Morrison and Smith,^{1 was found to have a current distribution similar to that of the classical insulated-base antenna, except near the grounded base. Therefore, the shunt-excited antenna should have nearly the same radiation properties as an insulated-base antenna having the same length and radiating at the same wavelength. The present work is an attempt to investigate theoretically whether and to what extent these predictions are justified. The current distribution is, therefore, calculated according to the ordinary simplified line theory. The radiation pattern is thereafter derived and a formula for the radiation resistance is found. The radiation resistance is calculated numerically as a function of the ratio "antenna-length/wavelength." It seems to be in many cases very different for a shunt-excited antenna than for an insulated-base antenna.}