Radiation in a warm plasma from an electric dipole with a cylindrical column of insulation

The radiation in a warm plasma due to an axially oriented electric dipole on the axis of a cylindrical column of insulation of infinite length is studied using the linearized continuum plasma theory, and approximate boundary conditions. Two types of surface waves are excited along the cylindrical column of free space immersed in a plasma and their dispersion and power relations are examined. The uncoupled electromagnetic (EM) and the plasma (P) space waves are excited. The radiation pattern and the normalized radiation resistance of the EM and the P modes are studied both as a function of frequency and as the radius of the insulating column. The effect of the insulating column is found to be very significant only in the case of the P mode. It is found that the power transfer into the P mode becomes less at higher frequencies and larger thickness of the insulation. The results of this investigation may be used to predict in a crude manner the effect of the "ion sheath" that is formed around the antenna in the ionosphere.