Ionospheric regions HF-Propagation

High frequency radio propagation between 3 Mhz and 30 Mhz is dominated by two ionospheric regions: E region (110 km above Earth) and F region (250-350 km), varying based on time, season, and solar activity.


Solar Activity

Radio propagation predictions rely on solar activity data from daily Sun observations, typically expressed as 10-cm solar flux, replacing sunspot counts for this purpose.