Theory of a thin biconical antenna located near the air-ground interface

Previous analyses of the input impedance of a thin biconical antenna are extended to include the effect of the air-ground interface. It is supposed that the antenna could be vertically located in the air or embedded in a spherical insulating cavity. The description of the basic theory is given and the electrical characteristics of the antenna such as the input impedance and the current distribution are determined, Illustrative calculations show that the air-ground interface changes the value of the input impedance but, as in the case of cylindrical antennas, the current dissymmetry only occurs if the antenna is situated very near the interface. Therefore, the shapes of the radiation patterns are nearly the same as those obtained by assuming a sinusoidal current repartition.