Analysis of Arbitrarily Shaped Wire Antennas Radiating Over a Lossy Half-Space.

摘要

The problem of an arbitrarily oriented current element over a lossy half-space is analyzed in this work. Various numerical approaches are developed and discussed for evaluating the infinite Sommerfeld integrals appearing in the vector potential expressions. In particular, a technique based on the steepest descent path integration is introduced for exact evaluation of these integrals, and, as an efficient alternative, an additional technique is developed based on approximating the well-behaved Fourier transform expressions of the Sommerfeld integrals. The latter technique has the merit of not requiring any time-consuming infinite integrations and, at the same time, is shown to yield accurate results for a wide range of parameters of practical interest. Finally, in this paper, the thin-wire antenna problem over a lossy half-space is analyzed via the method of moments and the current element solution techniques discussed earlier. Several antenna examples are included to demonstrate the effect of the lossy half-space on their input impedance and the far-field radiation patterns. (Author)