The objective of the project is to study the propagation of radio waves in the 40-m band in the ionosphere over South Africa. “For the purposes of this study, propagation can be defined as the ability of high frequency (HF) radio wave signals to travel through the upper atmosphere,” explains HMO Space Physics Group manager Dr Lee-Anne McKinnell. (HF covers the range 3 MHz to 30 MHz.)
Conditions in the ionosphere affect the propagation of radio waves, and can reduce their range, weaken them, and distort them. Obviously, the consequences for those employing HF radio communications can range from the irritating to the seriously disruptive. Conversely, ionospheric effects on radio wave propagation can tell scientists a lot about the structure and behaviour of the ionosphere.
“This is primarily an applied science project, being of direct importance to HF radio users, but it also has a pure science component,” reports McKinnell. “We will be able to take the propagation reports and use them to verify what we know is happening in the ionosphere from our theories of physics.”
The HMO is a national facility of the National Research Foundation, which falls under the Department of Science and Technology. Its original and continuing function is to monitor the earth’s magnetic field and is part of a global network of such observatories, but today it also has a technology group and the Space Physics Group. The SARL is the voluntary association which encompasses, represents, and supports the country’s radio hams.
This project involves the HMO making use of the SARL membership to create a nationwide network to study HF propagation in the ionosphere.
It will be implemented in two phases. In the first phase, which started last week, 28 simple radio beacons will be set up across the country, while phase two will add another 28, starting next year. These beacons will be spread across the country in a carefully planned network to provide the most possible information.
Two of the beacons will be hosted by the SARL and the HMO and will contain the functionality to use them for special events or competitions. The rest of the beacons will be hosted by licensed radio hams, which allows the HMO to deploy the beacons without having to get individual licences for each and every one of them, as the existing radio amateur licences automatically cover such transmitters. Each beacon is a 40-MW transmitter, operating on a frequency of 7,023 MHz, in the 40-m band, broadcasting in Morse code in the continuous wave mode; each beacon has a high resistance to lightning – a feature that has already been proved in practice.
Although only 56 hams will host beacons, any radio amateur can participate in the project by reporting recep- tion of the beacon signals, providing information on where he or she received the transmission, and how strong it was (which can be determined from the structure of the signal) – such information can be sent to the HMO by email, phone, or even ordinary mail. For the hams, this gives the very real satisfaction and excitement of participating in a serious research programme.
But this aspect of the project also opens the way for schools to participate. Equipped with the necessary receivers, learners can also monitor the beacons and submit reports to the HMO, bringing science and technology live into the classroom. And the SARL has developed a simple and cheap receiver for the schools. It will be supplied in kit form — the schools will not have to pay for them, as they will be sponsored. The plan is for local radio hams to help the children assemble the receivers.
Again, the result is that the learners, like the hams, will be participating with professional physicists in a real science project. To further stimulate the learners, some of the beacons will be transmitting ‘secret messages’ (which will change over time), and there will be competitions to see which schools are the first to decode these messages.
“This project is truly a collaborative project,” concludes McKinnell. “It will benefit the scientists, the hobbyists, and the schools.”