An experimental investigation on the behavior of the dipole antenna near the interface between the conducting medium and free space

An experimental study was made of the driving-point admittance and the relative amplitude and phase distributions of the current for a dipole antenna near and parallel to the interface between the conducting medium and free space. (The antenna was always located in the conducting medium, unless otherwise specified.) The depth
d
of the antenna from the interface was varied from
d/\lambda=4.4
to 0. The loss tangent
\sigma/\omega\epsilon_{r}\epsilon_{0}
of the conducting medium was varied from 0.036 to 8.8, a range which includes a variety of media such as poor insulators, the ionosphere, plasmas, dry earth, wet earth, lake water, and sea water. The antenna height
\beta h
in radians was varied from
\beta h=0.1
through
2\pi
. Comparisons were made, wherever possible, between the characteristics of the dipole antenna in the half space and in a space completely filled with the dissipative medium. The driving-point admittances in the limiting case
d\rightarrow \infty
are in good agreement with the available theories by King and Harrison [1], and Wu [2], which have already been verified experimentally by Iizuka and King [3]. Since all measured results are given in terms of dimensionless parameters such as
\beta h,d/\lambda_{u},\sigma/\omega\epsilon_{r}\epsilon_{0}
, and
1/\sqrt{\epsilon_{r}}
, they may be applied to any combination of conductivity, frequency, dielectric constant, and distance of the antenna from the interface [4].