Influence of profile shape on the bandwidth of a rotationally symmetric monopole

Rotationally symmetric antennas with asymptotically conical feed regions exhibit broadband impedance properties that are useful in many applications. The influence of the profile shape on the performance of this type of antenna has been investigated to some extent; but, for rotationally symmetric antennas, this has been limited to a few well-known designs, notably the "volcano smoke" monopole of Kraus, and the "asymptotic conical dipole" (ACD) of Baum. The purpose of this paper is to investigate the combined effect of alterations in the profile and of resistive loading on the impedance bandwidth. To accomplish this, analysis was carried out on a consistent modeling platform using the method of moments on a class of monopole antennas driven by a coaxial feed port and constrained to fit within a fixed hemispherical volume.