ARLA/CLUSTER: NVIS: Estudos de ionogramas na África do Sul mostram supremacia da banda de 5 MHz

[João Costa > CT1FBF]

Studies of ionograms show supremacy of 5 MHz band

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.

An article by Hannes Coetzee illustrated with ionograms is available
for download on the SARL 5 MHZ propagation Research page. Follow the
link from the SARL home page.

Fonte: The South African Radio League