Yes, according to scientists, the sun has gone quiet. Its activity has been recorded at a 100-year low (see www.spaceweather.com). So you may wonder, how does this impact our short wave radio signals? Richard Whittington, Feba’s Frequency Schedule Engineer, takes it all in his stride.

By studying the activity of the sun (sunspot high and lows), Richard can plan his bi-annual short wave programme schedules accordingly. He says: “During the period of low sunspot activity, I know not to schedule anything in the 19 or 16 metre radio bands, especially in the evenings and at night time, because signals will not be received.”

The sun has a usual 11-year cycle with its most active phase called solar maximum when dozens of sunspots burst out of it, and its quiet phase is called solar minimum (where it is currently) with no sunspots.

When Feba programmes leave the radio transmitter as short wave signals, these bounce off the ionosphere—the layer of earth's atmosphere that is ionised by radiation from the sun. When the sun has lots of sun spots the radiation is high, making the ionosphere very thick all day. When the sun activity is at its lowest, the higher frequencies (19 and 16 metre bands) will not carry signals, especially at night, because of the thin ionosphere.

More and more short wave radios have digital tuning, so people expect an exact science when tuning in. Short wave signals are bounced around and blocked due to sunspot activity, AND they are also impacted by seasons and time of day—so nothing in short wave is “exact”.

For example, radio signals on bands (shown in yellow above) between 49 and 31 metres are heard best in places where the sun is setting, because during the daytime these signals are absorbed by the ionosphere. Signals on the 25 metre band (during low sunspot activity) can be heard during the day and night, while the 22, 19, 16 metre bands will all generally be received best during the daylight. These are just some of the factors that Richard considers as he chooses short wave radio frequencies and times for Feba broadcasts to areas across Africa, Asia and the Middle East.

If these technical concepts of Feba radio interest you, check out the Feba schedule website for the latest summer and winter short wave schedules as well as a peek at the sun activity that Richard watches over: www.febaradio.net/