The input admittance of a prolate-spheroidal monopole antenna fed by a magnetic frill

The paper presents a theoretical study of a prolate-spheroidal monopole antenna. An experimental model was constructed for the antenna, and measurements made with this model were used to verify the theoretical calculations. There is generally very good agreement between the theory and the measurements. However, there are noticeable, small differences around the second resonant length. These differences are most likely due to two effects. The first effect is the fact that a perfect prolate-spheroidal shape could not be obtained for the experimental model. This can alter the effective electrical length of the spheroid. The second effect is the TEM field approximation that is used in the theoretical model.