Radiation from a Dielectric Coated Cylindrical Core Loop Antenna Surrounded by a Lossy Plasma Sheath†

Abstract

ABSTRACT The radiation of electromagnetic waves from a loop antenna in a cylindrically stratified media, one of which is a plasma, is considered. Amplitude and phase of the radiation pattern are calculated asymptotically. Numerical results showing the effects of plasma frequency and collision frequency on the radiation pattern (both the phase and amplitude) are presented. Numerical results for the case when there is no plasma are also included. It is shown in both the cases (in the presence and in the absence of the plasma) that the radiation pattern is more sensitive to the change in thickness of the dielectric coating or the plasma sheath than the same amount of numerical change of the dielectric constant of the medium (plasma or ordinary dielectric). At a very high frequency whether ωp/ω is less or greater than unity the radiation pattern is very directive. The angle of maximum radiation increases with the ratio ωp/ω for certain parameters. It is also shown that in some cases collision frequency helps ...