Propagation Predictions April 2014

Monthly HF Propagation Predictions from Gwyn Williams, G4FKH.

Data download -

The figures represent percentage availability, i.e. 1 means the path should be open between 1 and 19% of days, 2 means the path should be open between 20 and 29 percent of days, etc. The colours represent expected signal strength, i.e. Black = low to very low signals, Blue = fair signals and Red = strong signals.

Further information on the data

The above table has been compiled from a prediction model programmed by VE5ZX, the parameters and prediction engine options were supplied by G4FKH.

Clicking on a path name will produce an OPMUF/LUF (Optimum MUF/Lowest Usable Frequency) graph, depicting the two best bands for the path. When an unreliable path is suspected, the LUF graph line falls to zero and disappears.

The table represents median path predictions during quiet geomagnetic conditions and should be used with the following in mind. The monthly, cyclic and seasonal changes throughout any sunspot cycle are different because the sunspot and solar activity is either decreasing or increasing. Sunspot cycles are variable, some are very active whilst others are quiet and of course most are between these extremes.

To assist in the understanding of the table it is best to know where a specific station fits into the scheme of things.

These predictions were prepared for Mr. Average – Radio Amateur, using an average radio with a dipole type aerial, in a quiet urban environment. If a particular set-up is superior to this, it is only necessary to go up one colour and conversely if the set-up is less well off, then go down one colour. In all circumstances the percentage availability remains the same. However, it may be that some Amateur’s will never hear stations at the times when the numbers are in black.

There is an exception to the last paragraph, when longpath is being predicted, shown with (LP) following the path name. Higher input power has been used and a 3 element beam aerial for the higher bands. If a station is not thus equipped then it is unlikely that the longpath predictions will be accurate for that set-up.

Occasionally the table will include Dx-Peditions, when this happens, it should be taken into consideration that these particular predictions are produced using high power and beam type aerials.

The prediction engine REC533 has been utilised for the above predictions and is freely available from the NTIA/ITS download page.

Please email your comments and suggestions to g4FKH@sky.com