Worst cases for an one-hop high frequency link

The characterisation of a HF channel by means of monthly electron density profiles can be complemented with a detailed study of radio propagation worst cases on situations with extremes conditions of radiopropagation for a given period. These worst cases correspond to conditions that can be identified by means of cumulative distributions of the key parameter f0F2. In this paper, the main parameters of the HF channel: time delay, apogee, elevation angle and transmission frequency with mean and extreme conditions are analysed. The method used to characterise the ionospheric channel is based on ray-tracing techniques.