Propagation Research

Another Amateur Radio activity by the South African Radio League


16 March 2017

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Radio Communication via Near Vertical Incidence Skywave propagation  can be used for communication over a wide area. It is very well suited for emergency communication. It uses frequencies between 3 and 10 MHz with amateur allocation in the 5 MHz particularly attractive.  Two propagation researchers, Ben Witvliet  and Rosa Ma Alsina-Pages wrote an interesting paper with lots of reference to  other papers for additional reading.

You can download it here

New 5 MHz allocation for amateur radio agreed  at WRC15

New allocation for amateur radio service in the frequency band 5351.5 - 5366.5 kHz will maintain stable communications over various distances, especially for use when providing communications in disaster situations and for relief operations.  The South African Radio League has worked closely with ICASA and carried out propagation studies on two frequencies licensed by ICASA for this purpose.

It is not clear when the new allocation will be made available an replace the two frequencies that ICASA  allocated to members of the SARL. The current two licensed frequencies are 5260 and 5290 kHz .  ICASA have indicated that access to the new frequencies will likely only be from next year. The SARL has  discussed an interim solution with ICASA and has submitted a motivation to expedite the allocation. In agreement with ICASA we still use 5290 and 5260 MHz


SARL Members  will have access to 5 260 and 5 290  kHz on registration requiring the completion of a registration form which can be downloaded here.

Once completed please email it to Processing  time is a max three days.

All registered users are  listed  here

By: Stewart Moss ZS6SGM

Latest version V1.03 can now be down loaded here


If you are interested in the mysteries of propagation then WSPR is the tool at your disposal. To experience this fascinating tool, all you need is an SSB transceiver, simple antenna, a sound card interface to connect the transceiver to your computer and internet access. 

WSPR is short for Weak Signal Propagation Reporter and is pronounced “Whisper”. 

It is important to note right away that WSPR is not a QSO mode. It is used to broadcast a position, call sign and power level and see who hears and decodes it. The receiving station can work out how far the signal travelled and how strong it is on the receiving end.

The mode that WSPR uses is called MEPT-JT. MEPT means Manned Experimental Propagation Transmitter. The JT part is Joe Taylor's initials. Joe Taylor K1JT also developed the mode WSJT which is used for “moon-bounce” communication. In 1993 Joe Taylor shared a Nobel Prize in Physics with Russell Hulse, for some work they did in their field of Astrophysics. He obtained his license as an Amateur Radio operator as a teenager and as a result became interested in radio-astronomy.

This tutorial covers the reception and decoding of WSPR only. TX will be covered in later tutorial.   Download it here


The ionograms generated by the South African ionosonde network clearly illustrate the supremacy of the 5 MHz band for short range, near vertical incidence  skywave (NVIS) communications under certain conditions. These typically happens during the morning and late afternoon when the 7 MHz band does not support short range, sky wave communications and the 3.5 and 1.8 MHz bands suffer from high noise levels. 

During the middle of the day the 7 MHz (and 10 MHz during high solar activity) band is typically the most effective medium for short range, sky wave communications.

Permanent access to the 5 MHz band will ensure that the amateur radio community can efficiently contribute to emergencies requiring short distance communications beyond line-of-sight as typically required in hilly and mountainous terrain.

The South African ionosonde network is unique in Africa and place South African radio amateurs in the very fortunate position to monitor reigning, short range propagation conditions and to improve their skills and experience accordingly.

An article by Hannes Coetzee illustrated with ionograms is available for download  here