Arbitrary wire antenna above lossy half-space: rapid accurate image solution

Abstract

A simple, approximate, but very rapid and accurate image method is proposed for the analysis of arbitrary wire antennas above a lossy half‐space. The reflected field from vertical and horizontal Hertzian dipoles is approximated by the field of a few ‘optimally’ positioned simple elementary sources. The field of images is incorported into the Hallén‐type equations for the current distribution, resulting in equations of essentially the same form as those for an isolated antenna. The equations are solved by the point‐matching method and polynomial approximation of current along the antenna segments. The results for the impedance and admittance of antennas assembled of vertical, horizontal and/or oblique segments are in excellent agreement with the exact results (obtained from the Sommerfeld theory). The proposed method is conceptually very simple and on average 25 times faster than the exact method, although in some cases it was found to be faster for even two orders of magnitude. This makes it particularly suitable for numerical optimization and CAD of relatively complicated antennas and other wire structures above a lossy half‐space. © 1997 John Wiley & Sons, Ltd.