Radiation and impedance characteristics of a thin-wire transmission line-dipole system

Thin-wire transmission lines and dipoles, whose diameters are much less than the operating wavelength, carry currents which are essentially sinusoidal in form. Moreover, the electromagnetic field radiated by the filamentary (a to infinity ) straight wire of finite length can be specified exactly, even in the near zone of the wire. This made it possible for P.S. Carter (1932) to determine the input impedance by the induced-EMF method of dipole antennas with infinitesimal feed gap widths. E.C. Jordan and K.G. Balmain (1968) show that this method is equivalent to the Poynting vector method in which the complex radiated power is evaluated at a surface just outside the cylindrical surface of the actual thin-wire dipole. In the present study, this work is extended to consider not only the case of noninfinitesimal feed gap widths but also to include the parallel wire transmission line which is often used to supply energy to the dipole.<>