In a previous post from October of 2024, I reported how ZD7GWM on St Helena Island in the South Atlantic had managed to make contact with stations in Spain and Portugal on the 144 MHz (2m) band via Trans-Equatorial Propagation (TEP). During the spring of 2025, there have been similar openings from St Helena to Spain and Portugal.
On the 27th of April 2025, there was an unusual opening from ZD7GWM on St Helena to CT9ACF on the Madeira Islands. The distance was approximately 5,560kms and the transmission mode used was Q65D (60 seconds).
There are two unusual things about this 144 MHz contact...
1) It is as far as I know the very first contact ever between St Helena and the Madeira Islands on the 2m band.
2) At 144 MHz, TEP signals usually cross the geomagnetic equator at right angles i.e. 90-degrees. This means that the usual path is from St Helena to the southern regions of Spain and Portugal.
What's unusual here is that the geomagnetic equator begins to bend near the west coast of Africa allowing another TEP path to the Madeira Island region.
I'm just wondering why there aren't any contacts from the Canary Islands (EA8) to St Helena? Is anyone trying?
Lasse, SM0KAK sent on the very detailed report below...
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Unexpected QSO on 144MHz - ZD7GWM (St Helena Island) in IH74DB worked CT9ACF (Madeira Island) in IM12JU on 2025-04-27
Notes by SM0KAK
ZD7GWM has previously mainly made many QSOs with the South Western part of the Iberian Peninsula (the mainland of CT+EA) on 144MHz via TEP.
The QSO with CT9ACF was very unexpected!
The QRB 5561 km is normal for TEP on 144MHz. The time of day 22:00UTC is also expected for these longitudes, and the “normal” paths from ZD7GWM to EA4, EA7 and CT mainland were open.
This QSO was very unexpected because of
1) The wide footprint (CT9ACF is located very far from previous QSO partners)
2) The very bad takeoff at CT9ACF (in the direction towards ZD7GWM)
WIDE FOOTPRINT
Footprints of TEP on 144 MHz are normally less than 1000 km wide, and the possible directions is usually up to 10 degrees wide.
Stations located furthest from CT9ACF that have been worked previously worked by ZD7GWM are EA7KBX in IM87VK (1454 km from CT9ACF) and a single out layer QSO with EA3CJ last year in JN01SE (1899 km from CT9ACF). This makes the footprint much bigger than the expected 1000 km.
The QTF from ZD7GWM to CT9ACF is 347 degrees, the QTF to EA7KBX is 3 degrees, and to EA3CJ 6 degrees. Hence the difference in QTF is 16 degrees, which is much more than the expected 10 degrees.
This wide footprint could probably be explained by the very curved shape of the magnetic dip equator on these longitudes. The more curved it is, the wider footprint should is expected to be (assuming that you are located so that your signal can cross it with a 90 degree angle).
BAD TAKEOFF AT CT9ACF
CT9ACF has a very bad takeoff towards ZD7GWM. The elevation required to clear local mountains is about 7 degrees! The beacon ED8ZAA is in the same general direction as ZD7GWM. QRB is 498km and the beacon is located at 1000 masl. This beacon is rarely heard at CT9ACF. When it is heard it is usually via reflection off a minor island close to CT9ACF, or reflection off mountains in Morocco. But on this evening ED8ZAA was 599+ via the direct path! Good tropo propagation was forecasted, so the beacon was definitely heard via tropo. The strong beacon signal was the reason why CT9ACF wanted to try TEP with ZD7GWM for the first time. It is likely that the strong tropo was required to pass the local mountains. Elevation for TEP signals is normally low, in the order of 1 degree.
(There is a good example of mountains blocking a TEP path: FR5DN is very active on 144MHz TEP. His local mountain is at elevation of 4 to 5 degrees, and it limits his success quite a lot. He gets about 10% of the openings compared to FR4OO who has sea takeoff and is located about 38 km away. The openings at FR5DN are also shorter and weaker.)
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Tropo forecast around CT9ACF at the time of the QSO |
PROPAGATION
The QSO occurred while ZD7GWM had TEP to CT/EA, and while CT9ACF had tropo to ED8ZAA. The signals had very slow QSB, but faded 22:20 UTC. This is typical behaviour of TEP on 144MHz.
My conclusion is that propagation was TEP, plus tropo near CT9ACF. There was also tropo in the forecast at ZD7GWM that might have had an influence. However it seems very unlikely that this was a pure tropo QSO.
EQUIPMENT USED
Garry ZD7GWM has a good takeoff and is using 50W to a long vertically polarized omni directional antenna. He has been running TEP skeds on 100-150 evenings since September 2024!
Steve CT9ACF is using 2x9 element LFA yagis (horizontal polarization, vertically stacked). He is running 900W on EME, but less for terrestrial QSOs.
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Thanks to Lasse, SM0KAK for the above report. For more info on other long distance 2m openings, see my 144 MHz page.