AN EFFICIENT ANALYSIS OF VERTICAL DIPOLE ANTENNAS ABOVE A LOSSY HALF-SPACE

Abstract

The electromagnetic modeling of radiation by vertical dipole antennas above a lossy half-space is an important subject. The modeling often encounters Sommerfeld-type integrals that are normally highly oscillatory with poor convergence. Recently, an efficient computation of the electric field radiated by an infinitesimal electric dipole above a lossy half-space has been reported, in which the Sommerfeld-type integrals are reduced to rapidly-converging integrals. Using such efficiently-calculated electric field as the Green's function, in this paper, an electric field integral equation (EFIE) is formulated for the analysis of a vertical dipole antenna above a lossy half-space. Then, the EFIE is solved numerically employing the Method of Moments (MoM). Sample numerical results are presented and discussed for the current distribution as well as the input impedance and radiation pattern of the antenna. In particular, the EFIE solutions of the current distribution on an antenna in free space are checked with that obtained using a traditional approach of solving the Pocklington's equation. Also, the current distributions on an antenna above a very lossy half- space are checked by comparing them with that for the antenna above a PEC plane. Data of the current distribution and the input impedance show that for an antenna close to the media interface separating the two half-spaces, the electromagnetic parameters of the lower half-space can significantly affect the antenna characteristics. The radiation patterns of the antenna presented all exhibit properties as expected and similar to that documented in literature for infinitesimal vertical dipoles above a lossy half-space.