Ground loss effects in power line reradiation at standard broadcast frequencies

Reradiation of a standard broadcast antenna´s signal from a high-voltage power line is often analyzed by computer modeling. The resonant behavior of a power line operating over lossy ground is investigated using the numerical electromagnetics code (NEC) which uses the Sommerfeld-Norton (SN) ground model, for a highly accurate computation of the interaction of a power line with lossy ground. It is shown that lossy ground damps the resonant response of the power line and so, substantially reduces the reradiated field. Since the SN ground option is costly in CPU time, the effects of lossy ground were approximated using the tower footing impedance concept. A systematic evaluation of the accuracy of the approximation is made. An approximate technique for incorporating the approximate techniques presented are sufficiently accurate that the economical method-of-images solution can be used in most cases