Impedance of cylindrical and helical antennas in lossy magnetoplasma including conditions of refractive index resonance

A method is given to evaluate the input impedance of cylindrical and helical antennas immersed in cold lossy magnetoplasma. The impedance is shown to split into the sum of three terms associated, respectively, with the longitudinal current component, the circumferential current component, and the interaction between the two components of current. The procedure involves use of an assumed current density distribution for which necessary and sufficient conditions are obtained in order that the impedance will be finite for all frequencies including those for which there are refractive-index resonances. The method is applied to obtain extensive numerical results for a specific choice of current distribution for the special case when the antenna is aligned parallel to the static magnetic field. Indications of the sensitivity of the results to choice of current distribution for cylindrical antennas (longitudinal current only) are obtained by comparison of the present numerical results with numerical results in the literature based on other current distributions.