Ray‐tracing simulation of ionization trough effects upon radio waves

The propagation of high frequency electromagnetic waves through an ionosphere perturbed by a gaussian electron density trough is investigated using a three‐dimensional ray‐tracing computer program. Ray trajectories are presented for a normalized model ionosphere with troughs of varying width, depth, and distance from the transmitter. Focussing and defocussing effects are demonstrated to occur under special circumstances. Particular emphasis is placed upon simulation of records from fixed‐ and swept‐frequency sounding equipment. In particular, a moving trough is found to have unique Doppler signature which may be useful for ground‐based observational work.