This paper reports a study of an antenna system consisting of a vertical monopole and a small number of insulated horizontal radials lying lightly on the ground.
The monopole antenna has long been popular for medium frequency broadcasting because of its inherent simplicity and economy. Although quarter-wavelength resonant structures were used in the early days, it was shown by Ballantine (1924) that for a given power, the strongest field strength at the radio horizon was produced by an antenna about 0.6 wavelength long. This ignored the sky wave and was based on the assumption of a perfectly conducting (and reflecting) earth. With the same assumption, Brown (1935) computed the earth currents produced by a vertical monopole having a sinusoidal current distribution. He also estimated the ground power loss for a ground of infinite conductivity, assuming it had the same tangential magnetic field on its surface as when perfectly conducting. This is a reasonably good approximation under certain conditions and has been used by many writers following Brown (e.g. Wait &Surtees (1954), Monteath (1958), etc.)
