If you have been listening to the radio for any length of time you will have noticed that some
days or nights may be better than others for hearing your favourite stations. This is the effects of
propagation on the radio bands. This article will give you some very basic information on how
propagation will effect your listening and how you can use it to your advantage. The picture below will give you a real time view of where it is
daylight or night on Earth. The line dividing day and night is the gray line.
DAY VERSUS NIGHT- The 24 hour day is a cycle of light and darkness that has a major
effect on the entire radio spectrum from the lowest of frequencies to 30 MHZ where the
shortwave ends. A good rule of thumb is that signals above 9 or 10 MHZ are best in the day. On
the other hand at night you will find that stations below 9 or 10 MHZ coming in the best. In fact
as you go to the extremes of the radio spectrum the time of day becomes extremely important.
Frequencies below 5 MHZ are only useable at night, while those above 15 MHZ are useable in the
TIME OF THE YEAR- As you can see by the information above the amount of day light or
night time is vital. As the days become shorter and shorter the lower frequencies like those below
6 MHZ come into there prime. The reverse is true with the lengthening of the days so come the
better conditions for the higher bands. As the seasons change you will notice that many
international broadcasters will change their broadcast frequencies to insure that their audience can
still hear them. As an example if you were a broadcaster in Europe and wanted to reach an
audience on the East coast of north America about supper time or just after you would change up
in the spring and fall. In the fall and winter you would choose a frequency in the 7 or 6 MHZ
range. In the summer time you would use frequencies in the 12 or 15 MHZ range.
GRAYLINE DX'ING- The Grayline is the area of the world that is experiencing either a
sunrise or sunset. At these times of the day the levels of the atmosphere that radio signals bounce
off of to reach you are in a state of flux. All sorts of unusual effects can be observed at these times
and a good DX'er will take advantage of these events. If you know where on the globe it is
sunrise or sunset you can concentrate on these areas and see if you can pick up new and rare
stations. Do not forget to use your sun rise or sunset times to their advantage especially on the
AM broadcast band.
THE EFFECTS OF THE SUNSPOT CYCLES- As sunspot activity increases and decreases
over an 11 year cycle the bands you may chose to DX can change. These sunspots will have a
major effect on the upper atmosphere where radio signals reflect. As a rule as the solar cycle goes
to the up side, ie: more sunspot activity, the lower frequencies become less useable while the
higher frequencies become more active. The opposite is true, for as the sunspots drop off the
lower frequencies become much more DX'er friendly.
WWV INFORMATION- The time and information station WWV in Boulder Colorado or
station WWVH from Hawaii not only supply the time every minute but supply propagation
information. WWV gives out the information at 18 minutes after each hour. WWVH gives out
the information at 45 minutes after the hour. These stations operate 24 hours a day everyday of
the week. Both stations broadcast on the following frequencies:
2500 KHZ 5000 KHZ 10000 KHZ 15000 KHZ 20000 KHZ
Listen to them and you can find out what is going on propagation wise such a solar flares, storms
and polar cap absorption all of which will effect what you can hear.
BEACON STATIONS- You can set up your own beacon stations. Keep a list of how stations
that you can hear with regularity are coming in. If you have stations spotted around the globe you
can begin to gage how well that area of the world is coming in. Be careful to select stations not
only from different parts of the world but chose different frequencies. As you check these
stations on different frequencies from different areas of the globe, you will have a good idea of
what area of the world are coming in best on which range of frequencies. Once you establish
this you can go off and hunt for the targets you have set for yourself. This is a great way to get
new and rare stations.