Electromagnetic wave propagation on a thin wire above earth

The electromagnetic properties of a current on a thin horizontal wire above a flat lossy earth is reviewed. Attention is given to the historical devel opment of the topic, starting with the seminal work of Carson. Particularly , the importance of Professor Wait's contribution to the initial understand ing of the modal and radiative behaviors of the current, as described in hi s influential paper [1], is discussed in detail. A description of Wait's fu ll wave analysis is provided to show how that analysis justified many of th e assumptions embedded in Carson's result and how that same analysis later led to a fuller understanding of the current's spatial spectrum. Although n o rigorous proof is known to exist with respect to the completeness of this spectrum, a necessary condition for completeness is offered; the basis of this condition is the measurable input conductance of the wire. The paper c oncludes with a short discussion on the various extensions of Wait's classi c work that have been provided over the last two decades.