The Nature of Short Wave

Posted in Technical Information

Owning an expensive radio is not the answer to good listening. The largest factor in reception is determined by where your radio is located. High on top of a mountain is the best place, while the ground-floor flat dweller in a large city probably has the worst spot. A residential area generally provides a very satisfactory location. Wherever you stay, consider what affects reception and follow a few simple tips that will hopefully improve reception for you.

Short waves are transmitted over very long distances. Short wave signals bounce off the ionosphere and follow the curvature of the earth. The ionosphere, which is produced by the ultraviolet rays of the sun, consists of several layers of electrified particles encompassing the earth at a height of 100 to 300 km. The sun spot activity repeats in a cycle every eleven years and greatly affects short wave reception. Therefore, reception depends on the year, the season and the time of day.

TWR transmits several of its programmes on more than one meter band at the same time. Also, we change the meter bands throughout the day and in accordance with the time of year. The seasonal adjustments are normally carried out on the last Sunday of March and October and the broadcast schedules are updated accordingly.

Propagation

The radio signal from Swaziland will have covered a considerable distance before it reaches your radio. It may therefore suffer in quality. There are two main features of long range broadcasts worth mentioning.

  1. The ionosphere with its many layers is constantly shifting, subjecting the signal to occasional fading. This causes variations in signal strength. Hopefully this should not be serious and should still allow you to understand what is being said.
  2. The international broadcast bands are frequently very crowded and the many stations operating are in continual conflict for a clear spot. Occasionally another station may broadcast on a frequency very close to TWR. This is called interference. If you hear interference during our broadcasts, do not simply accept it. Often by fine-tuning your radio, you may be able to tune out the interference. Please report it to us. If we are aware of the problem it can possibly be rectified through our intervention. Within a few days you will notice that either the interfering station or TWR will have shifted frequency to a clear spot on the band.