Showing posts with label Madeira. Show all posts
Showing posts with label Madeira. Show all posts

Tuesday, April 29, 2025

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.

Friday, October 20, 2023

Madeira HF beacon CS3B destroyed in wildfire - Oct 2023


The radio beacon CS3B on the Portuguese island of Madeira was destroyed in a wildfire on the 12th of October 2023. The image above shows the destroyed radio and what the original ICOM 7200 would have look like. This new radio was only installed in September of 2023

The CS3B was part of the International Beacon Project which is a series of HF beacons operating on 14.100, 18.110, 21.150, 24.930 & 28.200 MHz.


The location of CS3B is shown above off the north-west coast of Africa and it was an ideal location for testing radio propagation on the HF bands to Europe and to North America.

The amount of fire damage to the site was quite extensive as the building housing the beacon was destroyed as well as the antenna as can be seen below.

It's very likely that any traps on the antenna will have been damaged as well by the heat and I suspect the whole antenna will need to be replaced.


The chart above from the Reverse Beacon Network (RBN) site shows the beacon operating on the 12th of October 2023 until it stopped suddenly around 15:00 UTC.


As can be seen from the chart above, the last reception reports were for 14:57 UTC.

Considering the extensive damage to the beacon and building, this HF beacon is likely to be off air for some time.

Link... IARU International Beacon Project