Infinite insulated cylindrical antenna in a simple anisotropic medium

Abstract

The characteristics of an infinite cylindrical antenna, insulated from the surrounding uniaxially anisotropic plasma medium by a concentric cylindrical sheath of free space, are investigated for the case in which the antenna is excited by means of a delta-function voltage source and the gyroelectric axis is parallel to the axis of the antenna. For sufficiently large thickness of the insulation, guided waves are found to be supported along the antenna and their dispersion and power relations are analyzed. The radiation conductance of the antenna contributed by the space waves is evaluated and is found to be practically independent of the insulation thickness for frequencies above the plasma frequency. For frequencies below the plasma frequency, the radiation conductance, which is infinite in the absence of the sheath, remains finite and decreases rapidly with the increase in the thickness of the insulation. The antenna current and the radiation pattern in the far zone are also examined.