Note on fictitious walls in eigenmode analysis of monopole antenna

Abstract

In order to evaluate the induced currents on the surface of a cylindrical monopole antenna located over a perfectly electric conducting ground plane using cylindrical harmonics, three kinds of fictitious walls, namely, an electric wall, a magnetic wall, and a combination of both, are artificially added above the monopole. The end effect, the thickness, and the source of the monopole can be taken rigorously into account in the computations. However, introducing fictitious walls definitely changes the field distributions for the different walls. In this paper, the comparison between the calculated field distributions for three approximations and solutions of the method of moment is conducted. The effects of these fictitious walls on the convergence of the impedance computations and the electric field distributions around the monopole are discussed. Some suggestions regarding how to choose the fictitious walls are given.