Fields excited by an arbitrarily oriented dipole in a cylindrically inhomogeneous plasma

In this paper we derive the closed-form solution of the three-dimensional fields excited by an arbitrarily oriented dipole in a cylindrically inhomogeneous isotropic plasma. Geometrical optics is used to represent the fields. The eikonal equation is solved to give the wave fronts from which the rays are obtained. A closed-form representation is obtained for the differential cross-section of a three-dimensional tube of rays thus yielding the amplitude of the wave. Closed-form expressions are also obtained for the normal vector, binormal vector, and torsion along the rays so that polarization is readily determined. For the special case where the antenna is located on axis, the radiation patterns depend only on the on-axis and peak electron densities. The solutions show good agreement with solutions obtained for a cylindrically stratified plasma in an earlier study.