Radiation from Transmission Lines

Abstract

The aim of this investigation was to contribute something to our knowledge of traveling electromagnetic waves. Among the transient phenomena that occur along transmission lines, these are still little known, especially as far as their ``attenuation'' and ``distortion,'' or change in shape near the ``wave front'' are concerned. It is first seen that the ``classical theory'' of the propagation of electrical disturbances along lines, as it has been chiefly developed by Heaviside and Poincare, does not give a correct representation of the facts near the wave front, because it assumes an instantaneous penetration, of the current in the wires. It is shown that this theory is an ``unidimensional'' one, as it considers only one space variable, the coordinate along the line, and, from an electromagnetic point of view, amounts to identifying the traveling waves with plane wave phenomena. Steinmetz's theory of the radiation from traveling waves (TRANS. A. I. E. E. Feb., 1919) is then examined, and, as Carson pointed out (JOUR. A. I. E. E., Oct. 1921), found based on a misconception of the propagation of the electromagnetic field near the wires of a line. It is remarked that this theory amounts to propagating longitudinal electric waves, a conception in conflict with the basis of Maxwell's theory. This latter proves very easily that, along a perfect line, i. e., without ohmic or leakage losses, plane electromagnetic traveling waves are propagated without distortion and without attenuation; hence that there is no radiation.