High‐frequency ray paths in ionospheric layers with horizontal gradients

The results of a study to determine the effects of horizontal gradients in the F 2 region electron density on short‐distance HF propagation paths (0–1000 km) are presented. Ray paths were obtained by employing specific models to represent the horizontal and vertical variations of the F 2 region. These models permitted ray path characteristics to be expressed by algebraic relationships. The changes in ray path characteristics with height of reflection, frequency, and azimuth are presented for gradients typically encountered on short‐distance HF propagation circuits over Europe.