On the effect of gap width on the admittance of solid circular cylindrical dipoles

Abstract

A center-fed, solid, circular cylindrical dipole of radius a with feed gap of width 2d radiating in a circular waveguide of radius b terminated in infinite ground planes is rigorously analyzed by applying both the conservation-of-complex-power technique and the multiple-reflections technique. The analysis begins by studying the dependence of the dipole admittance on its feed gap width and on its length, 2l, as well as on b, with ka (k=2 pi / lambda is the number) as a parameter. From the decreasing amplitudes of the almost periodic oscillations of these input admittances as b/ lambda is increased, the input admittances of dipoles radiating in free space (b to infinity ) are estimated using a variable-bound approach. The effect of gap width (d/a >