An experimental study of a monopole over a grounded hemisphere

Very little quantitative information is available on the behavior of an antenna over a nonplanar surface. A monopole over a metal hemisphere on a ground plane is a simple configuration which has possible applications to spacecraft antennas [1] and to broadcasting antennas erected on a hill. Measurements have been made of the driving-point admittance of a monopole with electrical lengths
\betah = \pi/2, \pi, 2\pi
as a function of the radius
b
of the hemisphere. A traveling-wave monopole with
\betah=2\pi
and
\betah_{T} = \pi/2
was also investigated. The current distribution on the hemisphere was measured by means of a movable probe.