Current Distributions on Helical Antennass

The current distribution on a uniform circular helix has been measured over a frequency band extending from 600 to 1,700 mc. Although the measured distributions are highly complex functions of distance and also change in an anomalous manner with frequency, it is possible to analyze the distributions in terms of traveling waves associated with three different transmission modes on the helix. The relative amplitude functions of these traveling waves, as well as their associated phase velocities, are approximated. Current distributions which have been calculated by superposing three or more traveling waves are in good agreement with the measured data.