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South African 5 MHz Research Project Sees Unexpected Results


A 5 MHz propagation research project in South Africa has encountered some unexpected results regarding near-vertical incidence skywave (NVIS) propagation on that band. The project is a joint venture between the South African Radio League (SARL) and the Kempton Park Amateur Radio Technical Society, where one 5 MHz beacon has been installed. An interesting, but tentative, finding was inconsistent NVIS propagation test results. NVIS takes advantage of skywave propagation for short-distance communication, especially on the lower end of the HF spectrum. An EE Publishers article described the preliminary test results.

“Comparing a communications path between two amateur stations, ZS6KN and ZS6KTS (distance of 51 km), it is interesting to note that in June 2014 there was a good communications path from just after [0500] till approximately 1630, after which the signals disappeared,” the article recounted, noting that the pattern for July was the same, but signals were considerably stronger than during August and September.

The experimenters also observed that the band opens earlier and closes later heading into summer (winter in the Northern Hemisphere), “which indicates variations in the ionization of the D layer of the ionosphere as the sun rises earlier and sets later,” the article said, noting, however, that not enough data have been collected to draw any meaningful conclusions.

The project uses several automated beacons using WSPR (Weak Signal Propagation Reporter), which was developed by Joe Taylor, K1JT.

The Independent Communications Authority of South Africa (ICASA) has awarded two licenses to the SARL to carry out 5 MHz propagation research in advance of World Radiocommunication Conference 2015 (WRC-15). Conference agenda item 1.4 would grant radio amateurs a secondary allocation within the band 5250 to 5450 kHz. Several countries, including the US, have allocated discrete channels to the Amateur Service on a secondary basis.





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