Spratly 2009

DXpedition to IOTA AS-051 in March 2009

Spratly 2009 header image 3

Propagation  

PROPAGATION PREDICTIONS

Predictions have been made for seven regions of the world:

DXers in other parts of the world can extrapolate the results for their locations, e.g. for those in Central and Eastern Europe the results should be between those of the Middle East and Western Europe, or for those in the Mid-West of the USA the results should be between those of the East Coast and West Coast of North America.

HOW TO INTERPRET THE PROPAGATION TABLES


For each of the seven locations there are two tables. The first is “Probability” and the second “Field strength”. The “Probability” table shows a predicted percentage, from “..” meaning 0%, up to “99″ meaning a 99% probability of the path being open between Spratly and the location stated, for each band and for each hour of the day.

The “Field strength” table shows a predicted received field strength in dBuV, assuming a 1kW transmitter and 0dBi gain antennas at both ends of the circuit, again for each band and for each hour of the day.

Clearly, the higher the figure in both tables the better. In practice, any value greater than about +1 in the Field strength tables should indicate workable signals, particularly if you have a beam antenna on the band in question. In the Probability tables do not ignore low values of Probability if the associated predicted Field strength is high. For example, to the Middle East at 0700UTC on 28.4MHz the predicted probability of the path being open is only 17%, but on the one or two days in a week that the band is open the predicted Field strength is 16dBuV, which should provide good signals. On the other hand, a high Probability figure does not necessarily mean that it will be possible to make a QSO: for example, to Southern Africa at 0700UTC on 14.2MHz the predicted probability is 99% but the predicted Field strength is -26dBuV, so although it is very likely that there will be some propagation between Spratly and Southern Africa, signals are likely to be too weak to make a QSO.

In addition to the above information, each table also shows the predicted frequency of the maximum useable frequency (MUF) and optimum working frequency (OWF) for the path between Spratly and the indicated location, for each hour of the day. The Field strength tables also give the predicted field strengths at the MUF and OWF (although this is less likely to be of use to you than the predicted Field strengths actually within the amateur bands).

Many thanks to Don Beattie, G3BJ, for producing the following tables.