Ray-tracing in the ionosphere for long range propagation studies

An ionospheric three-dimensional ray-tracing procedure on a world-wide scale is described which was applied at IROE for long-range propagation studies. This procedure is based on the numerical integration of the ray canonical equations originating from geometric optics and uses a three-dimensional model of the ionospheric electron density constructed from experimental data. The theoretical formulation of the problem is summarized; a description is given of the model assumed for the earth's magnetic field and of the procedure followed for modelling the electron density distribution. This procedure has the advantage that the world-wide behaviour is accurately represented with minimum memory requirement of the computer. The method for integrating the ray equations is outlined; particular attention was paid to the minimization of the machine time. Some ray-tracing results are presented displaying typical propagation modes.