FARADAY-ROTATION IN A COLD, INHOMOGENEOUS MAGNETOPLASMA - A NUMERICALCOMPARISON OF RAY AND FULL-WAVE ANALYSES

A numerical full wave analysis is used to determine the spatial variat ion of electromagnetic fields of a radio wave in a stratified ionosphe re. It is shown that the Faraday rotation may be accumulated as the an alysis proceeds by breaking the electric field into constituent charac teristic modes and accumulating phase. This has been achieved for vert ical, oblique, reflective, and transionospheric propagation. Compariso n of the full wave analysis with simpler methods of calculating the ro tation, such as ray tracing and very high frequency approximations, pe rmits the determination of the conditions under which these simpler me thods break down. It is found that ray tracing agrees very closely wit h the full wave analysis in most situations and always so for transion ospheric propagation. Some discrepancy between these methods appears w hen reflecting from severe vertical gradients where the full wave anal ysis is known to be required in accurately estimating the transmission coefficients. For reflective propagation at oblique incidence, small departures in the methods are also evident. Both methods converge to t he high-frequency approximation as the radio frequency increases above the peak plasma frequency.