The ionograms generated by the South African ionosonde network clearly illustrate the supremacy of the 5 MHz band for short range, near vertical incidence skywave (NVIS) communications under certain conditions.
These typically happens during the morning and late afternoon when the 7 MHz band does not support short range, sky wave communications and the 3.5 and 1.8 MHz bands suffer from high noise levels.
During the middle of the day the 7 MHz (and 10 MHz during high solar activity) band is typically the most effective medium for short range, sky wave communications.
Permanent access to the 5 MHz band will ensure that the amateur radio community can efficiently contribute to emergencies requiring short distance communications beyond line-of-sight as typically required in hilly and mountainous terrain.
The South African ionosonde network is unique in Africa and place South African radio amateurs in the very fortunate position to monitor reigning, short range propagation conditions and to improve their skills and experience accordingly.