Analysis of Wire Antennas in the Presence of a Conducting Half-Space. Part I. The Vertical Antenna in Free Space

Abstract

An integral equation method (based upon the electric field) for the analysis of a vertical antenna located in free space near the interface with a lossy half-space is presented. Two methods are considered to account for the influence of the interface-reflected fields upon the antenna current distribution: (1) the rigorous Sommerfeld integral approach and (2) a plane-wave reflection coefficient approximation. Numerical results for antenna impedance from the two methods are compared. It is found that for the parameter variations studied, the reflection coefficient approximation provides results within 10% of those obtained from the rigorous approach at approximately 1% of the computer time. The reflection coefficient technique has the further advantage of being readily extended to arbitrary antenna geometries and orientations.