Unusual 5560km TEP opening on 144 MHz from St Helena to Madeira Is - Apr 2025

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.)

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.

Guest Post: Some thoughts on VHF paths across the South Atlantic ...by Dave, N7BHC

Dave N7BHC (Also PJ4VHF & ZR2BI) left a comment on a post recently about VHF propagation in the South Atlantic. There was so much interesting info in it that I have put it up here as a guest post. There is plenty in there as food for thought.

* * *

Back in 2007-2010, I was trying to drum up trans-Atlantic tropo ducting interest. I am very pleased to see more progress now. A contact from ZD7 (St.Helena Is) to PY (Brazil) on 144 MHz (2m) is 100% probable. 

I introduced John Turner at Saint FM, the local FM radio station, back in 2008-2010 to tropo ducting on the FM broadcasting band. He successfully logged many Angolan, Namibian, and Cape Town FM stations. One December he emailed that he was unsuccessful identifying an Angolan FM radio station as he had interference from a Brazilian station on the same frequency. This was using just a car radio with its whip antenna. 

Back in March 2008, ZD8I on Ascension Island reported that they sometimes heard Cape Town Marine Radio (ZSC) on 156.8 MHz FM. That is an omni antenna to an omni antenna on FM at a range of 4400 km. 

ZD8S on Ascension Island reports listening to Brazilian FM stations with indoor portable radios. 

Since then, I spent the next ten years on Bonaire as PJ4VHF. My biggest tropo ducting success across the North Atlantic was the initial reception of D4C/b on the Cape Verde Islands at a range of 4,694km. I strongly encourage any stations on ZD7 and ZD8 to be active on both 2m and 70cm. 

I have been studying trans-ocenic ducting for many decades (I started out as ZR2BI in East London). The South Atlantic may be the BEST location worldwide for long-haul ducting, both for range and how often the openings occur. FM vertical polarization works well bit SSB or FT8 on horizontal is even better.

Maybe someday we may be allowed to and able to travel again, and I can afford to visit ZD7 in person. Until then, all I can do is strongly encourage others. 

73, Dave N7BHC/PJ4VHF/ZR2BI dpedersen AT drasticom DOT com

New 144 MHz beacon on St Helena Island heard over 3000kms away in South Africa - 1st March 2021

Back in February of 2021, I had a post up about the new 144 MHz on St Helena Island in the South Atlantic. Now we have the first reception report!

On the 1st of March 2021, Charles ZS1CF in Cape Town heard the ZD7GWM beacon on St Helena Island over a distance of approximately 3145 kms. The beacon operates on 144.475 MHz with 25 watts on CW into a vertical antenna.

The tropo prediction map above from Pascal, F5LEN shows path and it is believed that the propagation mode was via a maritime duct just above the ocean.

This marine path from South Africa to St Helena is a relatively common occurrence and successful contacts have been made on 2m and 70cms in the last few years. It is hoped that the new beacon will give a better picture of just how often this 3000km+ path opens and encourage others to have a listen as well.

As outlined in the original beacon post, there may be a possibility of a 144 MHz trans-Atlantic path to Brazil or via TEP to Europe.

Link...

1) Update on the new 144 MHz beacon on St Helena Island (ZD7) - Feb 16th 2021

3000km plus contact made on 433 MHz from St.Helena to South Africa - 16th Oct 2020

On the 16th of October 2020, there was a remarkable 3000+ km contact made on the 70cms band between South Africa and St.Helena in the South Atlantic.

The contact at 433 MHz was made between Garry, ZD7GWM on St.Helena Island and Tom, ZS1TA in South Africa. The distance was approximately 3136 kms and what was even more amazing was that the contact was made on FM!

The power used for the contact was a modest 35 watts into a vertical antenna. This was a new distance record for a contact between South Africa and St.Helena on the 70cms band.

The mode of propagation was probably a marine duct as shown by this tropo forecast map from Pascal, F5LEN.

This 3000km+ tropo path between South Africa and St.Helena opens up on a reasonably regular basis. Back in November of 2018, there was an opening on 144 MHz as outlined in this previous post.

In June of 2020, the 2m path opened up again and the most recent opening on 2-metres was on the 23rd of September 2020 when ZD7GWM was worked by no fewer than five ZS stations... ZS1TA, ZS3CVB, ZS1CF, ZS3JPY and ZS1FC.

To put these remarkable contacts on 144 MHz and 433 MHz into context, the 3136 km distance is equivalent to the path across the North Atlantic between Newfoundland and Ireland.

Link...

1) Cape Town Amateur Radio Centre: ZS1TA & ZD7GWM Set New 70cm Distance Record - 16 Oct '20