Impedance of a short dipole antenna in a cold plasma

This paper presents the analysis of the impedance of a short dipole antenna in a cold plasma using a quasi-static approach. Two radically different current distributions on the antenna are considered and their influences on the antenna impedance are studied. These distributions include a one-dimensional (1-D) triangular distribution and a three-dimensional (3-D) exponential current distribution. Balmain (1964) analytically solved the first problem. Staras (1964) proposed the second one. In this paper, we offer an analytical solution for the second one as proposed by Staras. We compare both distributions and find that impedances resulting from them are remarkably close. We conclude that the impedance of a short antenna, as derived using the quasi-static approximation, is insensitive to the choice of current distribution. Therefore, any of these two theories can be used when analyzing data from an impedance probe immersed in a space plasma.