The application of Step-Changing technique in ionospheric ray-tracing

Starting from ray equation, the ray parameters can be solved by using the Runge-Kutta method. The integral step can be adjusted automatically according to the gradient of the electron density, which is called Step-Changing technique. Examples were presented to show the efficiency of this technique for the quasi-parabolic layer and equatorial double torus model. The results show that this technique gives a great improvement in the speed of ray-tracing, while the accuracy has been maintained.