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 development of the topic, starting with the seminal work of Carson. Particularly, the importance of Professor Wait´s contribution to the initial understanding of the modal and radiative behaviors of the current, as described in his influential paper (see Radio Sci., vol.7, p.675, 1972), is discussed in detail. A description of Wait´s full wave analysis is provided to show how that analysis justified many of the assumptions embedded in Carson´s result and how that same analysis later led to a fuller understanding of the current´s spatial spectrum. Although no 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 concludes with a short discussion on the various extensions of Wait´s classic work that have been provided over the last two decades