D4VHF on Cape Verde not active on 144 MHz due to antenna damage - May 2021

In response to a recent query, one of the D4VHF team has confirmed that their 144 MHz VHF station is off air at present.

Andrea, HB9DUR writes... “I am sorry to disappoint you re. D4VHF but the station is not fully operative, especially on 2m.

Monteverde has been suffering from non stop high winds from Christmas last year till some weeks ago.

So the yagi to west is heavily damaged by strong winds, the towers as well are not in a good shape. Moreover no power amplifier is available until somebody can travel there….“

The D4VHF station on Cape Verde off the west coast of Africa has in recent years has been responsible for some of the most spectacular contacts on 144 MHz and 432 MHz to Europe and across the Atlantic to the Caribbean.

For the moment (May 2021), they are still active on 50 MHz and the QO-100 satellite.

D4VHF on Cape Verde plans to be on the 70 MHz band during the Summer of 2021

The D4VHF team on Cape Verde Islands have just announced that they plan to be operational on the 70 MHz (4-metre) band during the Summer of 2021!

They will be using a 4-element Yagi (shown above) beaming towards Europe with an output power of 500-watts.

As the map shows below, the Cape Verde Islands are a long way from Europe and some multi-hop propagation will likely be required.

Analysis... The annual Sporadic-E season in the northern hemisphere normally starts in late April and runs until mid-August. 

It's likely that the first Sp-E openings from Cape Verde will be single hop with a maximum range of 2300kms or so. Stations in the Canary Islands (EA8) at 1500kms or so are ideally placed for a one-hop Sporadic-E opening on 70 MHz.

To get further up and into Europe, it will likely require a double hop opening with ranges of say 2500 to 4400 kms. This should allow stations in the UK and Ireland to work Cape Verde on 4m.

Obviously the more hops that are required for a path to open then there are statistically fewer openings. However, 70 MHz isn't that high a frequency when it comes to Sporadic-E and there should be occasions when even three hops or even four hops are possible. I suspect though that multi-hop openings like this to say central or northern Europe may only occur once per season? We'll see.

Tropo Ducting at 70 MHz???... The D4VHF station on Cape Verde has made many spectacular contacts on 144 MHz and 432 MHz thanks to a marine duct off the north-west coast of Africa.

This marine duct establishes itself for long periods at different times of the year and this allows stations on the coast of Spain and Portugal to work D4VHF on 2m with relative ease over a 3000km or so path. At times, this duct moves further north allowing stations in the UK and Ireland to get in on the action.

This duct behaves like a waveguide and it has certain dimensions. As such, like a waveguide it will have a lower cut off frequency below which signals will not propagate.

The big question is if 70 MHz signals with a wavelength of four metres will be able to propagate through this marine duct?

Will the 70 MHz signals from D4VHF be able to reach the Canary Islands (~1500kms) by tropo ducting? The south-west coast of Spain and Portugal at 2800kms? Will the frequency be too low?

If the marine duct does propagate 70 MHz signals then there is the possibility of it coupling to Sporadic-E openings more often. If not then it looks as if rarer double hop Sp-E might be the only option.

In conclusion... I'm sure many fans of the 70 MHz band will look forward to D4VHF from Cape Verde appearing on the band during the summer of 2021. Single hop and even double hop Sporadic-E contacts I believe are a forgone conclusion and these shouldn't be that difficult.

What I find most interesting however is the ability of a 70 MHz signal to propagate inside a marine duct. Is it possible? If it does happen, is it common? And how far?

It'll be interesting to see the results.

4000km VHF opens up from NW Europe to Cape Verde Islands - 22nd July 2020

Over the last few days, there have been another opening from the north-west of Europe on the VHF and UHF bands to Cape Verde Islands off the west coast of Africa. The map above shows the opening on 144 MHz on the 22nd of July 2020 with many of the FT8 signals from D4VHF around the 4000 km mark.

xmtr Rcvr Band Mode Distance Time (UTC)
D4VHF GW4VXE 2m FT8 4280 km 19:01:11
D4VHF GW1JFV 2m FT8 4264 km 21:31:14
D4VHF GW6TEO 2m FT8 4249 km 20:44:14
D4VHF EI8KN 2m FT8 4230 km 20:57:11
D4VHF EI2FG 2m FT8 4182 km 19:51:41
D4VHF M0BKV 2m FT8 4181 km 22:49:14
D4VHF EI3KD 2m FT8 4170 km 22:22:14
D4VHF G4LOH 2m FT8 4098 km 23:26:14
M0AFJ D4VHF 2m FT8 4094 km 19:52:26
D4VHF G3NJV 2m FT8 4090 km 21:34:14
D4VHF G7RAU 2m FT8 4086 km 23:25:11
D4VHF F6KHM 2m FT8 3966 km 22:25:14
D4VHF F8DBF 2m FT8 3963 km 22:39:14
F6DRO D4VHF 2m FT8 3870 km 15:30:26

The path was also open on 432 MHz...

As with previous openings of this type, the path is marine ducting. There seems to be almost a permanent 3000 km path from Cape Verde to Spain & Portugal at certain times of the year and this pushes northwards towards the UK and Ireland from time to time.

Just to give an idea of how good this opening was, Tim GW4VXE in the far SW of Wales reports hearing D4VHF on 70cms with a vertical!

It would be really interesting to see if this path extends up into the microwave bands, especially on 1296 MHz.

Upgrade of the D4VHF station VHF & Microwave antenna systems

Over the last few years, the D4VHF station in the Cape Verde Islands has made some amazing contacts on the 144 MHz & 432 MHz bands across the Atlantic to the Caribbean and also well into Europe. Most of these VHF and UHF contacts are in the region of 3000 to 6000 kms.

They recently made some major changes to their antenna system for 2-metres, 23cms and 12 cms.

2-metres... Up to recently, the D4VHF team were using a single 12 element Yagi on 144 MHz. They have now installed three crossed 5-element Yagis.

The photo above shows the three new 144 MHz crossed Yagis marked A, B and C. As can be seen, the three crossed Yagis are stacked vertically.

This second photo above shows the stacked Yagis from a different angle. Each individual crossed Yagi is made of two 5-element beams in a X configuration. These two beams are  fed 90 degrees out of phase relative to each other and this achieves Right Handed Circular Polisation (RHCP).

Comparison - Old 12 element Yagi V New Stack of three 5-element RHCP Yagis... How do the two antenna systems compare? Here are some rough calculations...

Gain... The old 12 element Yagi which was horizontally polarised probably had a free space gain of about 13dBd.

As for the new stack? Let's take the gain of 5 element beam to be 9dBd. There is a stack of three so lets add 5dB giving a gain of 14dBd. Lets assume that there is some loss stacking as they will probably not get the full three times power so we'll subtract 0.5dB giving 13.5dBd. There is also a 3dB loss due to the fact that it is using circular polarization and we're down to about 10.5dBd.

So we have an estimated 13dBd for the old 12 element and 10.5dBd for the new antenna system, a drop of about 2.5dB.

Linear Vs Circular Polazation... When both the receive and transmit antennas are horizontally polarized at either end of a propagation path and nothing changes then everything is fine. However when the path is several thousand kms in length, will it always stay the same? If there happens to be a Sporadic-E hop involved then the polarization of the signal is constantly changing.

If say a horizontally polarized antenna receives a horizontally polarized signal then there is no loss i.e. 0dB. If however a signal gets twisted and arrives at more than 45 degrees relative to the receive antenna, then the losses can be anything from -3dB up to -20dB.

With very weak FT8 signals buried in the noise and with 15 second transmissions, this polarization fading can mean incomplete contacts or at the very least, it slows things right down resulting in fewer contacts during say a Sporadic-E opening.

With a circularly polarized antenna, the loss is never more than -3dB. So even though the gain of the new antenna stack is slightly less, the lower loss due to polarization changes should result in more completed contacts.

Beamwidth... The other change between the new and old systems is the beamwidth.

The beamwidth of a beam is measured by its -3dB points i.e. where the gain of the antenna has dropped by 3dB.

For the old 12 element antenna with a gain of about 13dBd, the beamwidth was about 32 degrees.

With the new antenna array, the vertical stacking will compress the radiation in the vertical plant and direct more of it down towards the horizon. For the radiation in the horizontal plane i.e. left/right, it should have pretty much the same beamwidth as a single 5 element which is about 54 degrees.

This map shows the beam headings from Cape Verde to Europe...

With the old 12 element pointing at 35 degrees, the 32 degree beamwidth covered about 19 to 51 degrees.... roughly from Wales to the south of Italy.

With the new array for the same 35 degree example, the 54 degree beamwidth will extend from 08 to 62 degrees. This means that there is more power heading towards say Ireland, Scotland and the Azores.

It also allows more power to head towards the Eastern Mediterranean. It seems unlikely that someone from say Greece or Israel could work D4VHF on 144 MHz as there is a lot more land and less sea for a marine duct. But that's not to say its impossible, especially at this more southerly latitude.

Microwave Bands.... They also made some improvements to their set up for the microwave bands of 23cms and 13 cms.

The photo above shows the 1-metre homemade dish for 1296 MHz and 2300 MHz. The gain on 23cms is approx 19dBd while the gain on 13 cms is about 24dBd. They will be adding an elevation motor so that it can be used for moonbounce.

This is another view of the same dish but it also shows the 80cm dish on the right for accessing the QO100 satellite in geostationary orbit (2.4 GHz up, 10 GHz down).

In conclusion... As you can see, the D4VHF team are constantly improving their station on Cape Verde and are opening up new paths that we didn't even know existed.

If you would like to support their work then they have a PayPal link HERE

5000km plus opening on 144 MHz from Cape Verde Islands to Italy, Slovenia & Croatia - 2nd July 2020

On Thursday the 2nd of July 2020, there was another remarkable opening on 144 MHz between Cape Verde Islands off the west coast of Africa and Italy, Slovenia & Croatia.

This isn't the first time that this has happened but any terrestrial opening on 144 MHz which reaches 5000kms or more is always special.

This edited list shows the stations that heard by D4VHF in Cape Verde. It also lists those hearing D4VHF on FT8 but not weren't heard by them (in order of distance)...

Txmtr Rcvr Band Mode Distance Time (UTC)
D4VHF S51ZO 2m FT8 5028 km 19:09:59
9A5BWW D4VHF 2m FT8 5013 km 19:02:42
D4VHF 9A6NA 2m FT8 5013 km 18:51:56
D4VHF S50TA 2m FT8 4885 km 19:17:44
D4VHF S57A 2m FT8 4809 km 18:41:59
D4VHF IV3/HB9CAT 2m FT8 4798 km 18:27:59
D4VHF IV3GTH 2m FT8 4792 km 18:41:56
9A5CW D4VHF 2m FT8 4790 km 19:17:57
D4VHF IV3GBO 2m FT8 4786 km 19:11:44
9A3CX D4VHF 2m FT8 4776 km 19:03:12
D4VHF IV3BLQ 2m FT8 4776 km 19:17:41
D4VHF 9A5CW 2m FT8 4774 km 19:17:14
D4VHF 9A3K 2m FT8 4774 km 19:15:44
D4VHF 9A1UN 2m FT8 4766 km 19:04:29
9A2RD D4VHF 2m FT8 4766 km 19:01:41
IK3VZO D4VHF 2m FT8 4643 km 18:35:12
D4VHF IW3GJF 2m FT8 4639 km 18:35:29
IZ3NOC D4VHF 2m FT8 4636 km 18:32:11
D4VHF IK4DRY 2m FT8 4624 km 18:59:29
D4VHF IK4FMT 2m FT8 4596 km 18:59:26
D4VHF IW4AZY 2m FT8 4548 km 19:11:15
D4VHF IK2MKS 2m FT8 4528 km 15:51:44
IK2LHP D4VHF 2m FT8 4517 km 15:57:56
IK0SMG D4VHF 2m FT8 4506 km 16:44:56
D4VHF IW0FFK 2m FT8 4505 km 16:46:44
D4VHF IZ2MHO 2m FT8 4480 km 15:52:11
D4VHF G7RAU 2m FT8 4086 km 16:02:14

FT8 screenshot from D4VHF

This is a list of the 20 stations in Italy, Slovenia & Croatia that D4VHF actually completed a contact with on FT8...

2020-07-02 15:49:15 IZ2MHO JN45 144.175900 FT8 +03,-06 
2020-07-02 16:30:30 IK0SMG JN61 144.175900 FT8 -03 -11 
2020-07-02 18:25:00 IK3VZO JN55 144.174900 FT8 -19 -01 
2020-07-02 18:28:00 S50TA 144.174900 FT8 +08 +01 
2020-07-02 18:28:30 IZ3NOC 144.174900 FT8 -03 -12 
2020-07-02 18:33:00 IV3NDC 144.174900 FT8 -06 -06 
2020-07-02 18:34:30 IW3GJF 144.174900 FT8 -12 -06 
2020-07-02 18:36:45 IV3GTH JN65 144.174900 FT8 -17 -11 
2020-07-02 18:37:45 IZ3QFG 144.174900 FT8 -05 
2020-07-02 18:42:30 S57A JN65 144.174900 FT8 +02 -06 
2020-07-02 18:44:00 IK4FMT JN54,144.174900 FT8 -15 -21 
2020-07-02 18:46:45 IK4DRY 144.174900 FT8 -11 -07 
2020-07-02 18:52:00 9A3CX JN65 144.174900 FT8 +00 -01 
2020-07-02 18:57:30 9A3K JN65 144.174900 FT8 +05 +01 
2020-07-02 18:58:15 9A6NA JN86 144.174900 FT8 -12 -19 
2020-07-02 19:02:00 9A2RD JN65 144.174900 FT8 +13 -09 
2020-07-02 19:02:45 9A5BWW JN86,144.174900 FT8 -05 -16 
2020-07-02 19:04:30 9A1UN JN65 144.174900 FT8 -10 -07 
2020-07-02 19:05:45 IV3GBO JN66 144.174900 FT8 +17 -07 
2020-07-02 19:12:30 9A5CW JN65 144.174900 FT8 -06 -13 

Another screenshot from D4VHF

Mode of Propagation... How exactly did these 5000km signals travel so far on 144 MHz? It seems likely that it was via a combination of a marine duct from Cape Verde up as far as Morocco and via Sporadic-E from there to Italy.

The tropo prediction map from Pascal, F5LEN shows some tropo in the Mediterranean Sea so that can't be discounted either. However, there must surely been at least one Sporadic-E hop in there somewhere.

Full D4VHF log including the EA & EA8 stations shown below...

Amazing 5600 km opening on 144 MHz from Cape Verde Islands to Poland

This post is now in two parts.

The original post is shown in Part 1 below.

The updated information with the log from D4VHF is shown in Part 2 further down the post.

* * * * *

Part 1...

On Friday the 29th of May 2020, there was an extensive Sporadic-E opening across Europe which reached as high as 144 MHz allowing stations across the continent to make many fine contacts.

The most extraordinary contacts however was probably the opening from the Cape Verde Islands off the coast of Africa to Poland on 144 MHz. The longest path recorded seems to have been when the FT8 signals from D4VHF were heard by SP5XMU in Warsaw, a distance of just over 5,600kms.

The map above shows the stations on FT8 that reported hearing or were heard by D4VHF. The most intensive part of the Sporadic-E seems to have been along a narrow corridor stretching from Lyon in France to Warsaw in Poland.

Mode of Propagation... It seems very likely that there were two propagation modes at work for this extraordinary path from the Cape Verde Islands to Central Europe.

As shown by the tropo prediction map above courtesy of F5LEN, there is a reasonably stable maritime tropo duct from the Cape Verde Islands to south coast of Portugal, a distance of about 2,800kms.

The path from Poland to the south-west of the Iberian Peninsula was spanned by a Sporadic-E opening which was in progress across Europe at the time.

As with openings of this nature, there is always the possibility of double hop Sporadic-E which can't be discounted for a good part of the path. However, this tropo duct off the north-west coast of Africa is a remarkably steady feature and it seems to be there for a large part of the year. It's hard to imagine that it didn't play a major part in the opening.

FT8 screenshot from D4VHF

In 2019, there were other similar mixed Sporadic-E & tropo duct openings from Cape Verde to Italy and Germany. The distances involved with this opening to Poland though are exceptional.

* * * * *

PART 2...

Update. Now that the dust has settled, we can look at the log of D4VHF and who they worked...

While many stations heard D4VHF on FT8, a much smaller number managed to make a contact.

Here is the log...

2020-05-29,10:05:15, CT1END,IM58,144.175900,FT8,-07,-04,,,
2020-05-29,11:10:00, IK4ADE,JN54,144.175900,FT8,-07,-09,,,
2020-05-29,11:57:15, IK0ZYH,JN62,144.175900,FT8,-15,-17,,,
2020-05-29,12:15:45, EA8AJC,IL18,144.175900,FT8,+28,+17,,,
2020-05-29,12:36:00, F6EAS,,144.175900,FT8,+04,+02,,,
2020-05-29,12:43:30, EC1KV,,144.175900,FT8,-15,-15,,,
2020-05-29,12:49:15, F1DUZ,IN97,144.175900,FT8,-18,-19,,,
2020-05-29,12:52:00, F6CIS,,144.175900,FT8,-15,-19,,,
2020-05-29,12:59:45, F6DBI,IN88,144.175900,FT8,-03,-07,,,
2020-05-29,13:22:30, F8DBF,IN78,144.175900,FT8,-06,-08,,,
2020-05-29,13:47:00, G4RRA,,144.175900,FT8,-15,-16,,,
2020-05-29,13:49:00, G8BCG,,144.175900,FT8,+00,-16,,,
2020-05-29,13:52:00, GW7SMV,,144.175900,FT8,-05,-16,,,
2020-05-29,13:54:30, G3NJV,IO70,144.175900,FT8,-15,-01,,,
2020-05-29,13:55:30, G7RAU,IN79,144.175900,FT8,-13,-13,,,
2020-05-29,14:19:15, CT1IUA,IM67,144.175900,FT8,-16,-12,,,
2020-05-29,15:27:00, DJ8RZ,JN58,144.175900,FT8,-08,-10,,,
2020-05-29,15:30:45, DL5MCG,,144.175900,FT8,-09,-19,,,
2020-05-29,15:34:45, I2FAK,JN45,144.175900,FT8,+10,-11,,,
2020-05-29,18:41:15, CT1ANO,IN51,144.175900,FT8,-18,-19,,,
2020-05-29,18:55:15, CU2GI,HM77,144.175900,FT8,-19,-18,,,
2020-05-30,08:39:45, EA8AIN,IL18,144.175900,FT8,-09,+08,,,
2020-05-30,16:21:30, EA7FDW,IM76,144.175900,FT8,-11,-12,,,
2020-05-30,16:44:45, EA7E,IM66,144.175900,FT8,-18,-20,,,
2020-05-30,16:49:45, CT1EYQ,IM58,144.175900,FT8,-18,-17,,,
2020-05-30,17:16:45, EC2AGL,IN91,144.175900,FT8,-06,-16,,,
2020-05-30,17:22:45, CT1ADT,IM57,144.175900,FT8,-13,-07,,,

The FT8 signals sent and received by D4VHF according to the PSK Reporter website are shown at the end of this post.

Some points...

1) SSB V FT8... For a Sporadic-E opening on 144 MHz, a mode like SSB would be much better in terms of speed. However, look at the signal strengths in the log. Most are in the minus dB range so a SSB QSO would probably have not been possible.

As for what would be a better mode is up for debate. Marginal contacts via CW? Faster digital modes like FT4? No matter what mode was used, there would have always been incomplete contacts and a limit to how many would get in the log.

2) Mode of Propagation... From what we know, there seems to be two components.

First, there is a marine duct off the west coast of Morocco which allows VHF signals to propagate from Cape Verde Islands up to the Canary Islands (1500kms), Portugal & Spain (3000kms) and the UK (4000kms).

According to one of the operators of D4VHF...Mark EA8FF, there was no tropo between D4 and EA8 or EA7 at the time. And yet, this marine duct over the sea was probably present for a good part of the path. I don't think we can discount it and yet, there must surely be Sporadic-E openings on 144 MHz in that part of the world as well? We can't always assume it's a marine duct.

While we can debate the paths from D4 to the coasts of Portugal or the south of Spain, those signals from further north were almost certainly via Sporadic-E.

The question is was it tropo & Sp-E, multi-hop Sp-E at 144 MHz?? Just in terms of probability, I personally don't believe in triple hop Sporadic-E at 144 MHz. Double maybe, triple?!?!

3) Sporadic-E to the UK... The problem with just a list of stations is that there are like data points for a graph, they don't make much sense until you draw the graph. In the same vein, when you generate a map and see the location of the stations, you can see patterns.

Again, see the map above. Note how the UK stations are strung out in a nice narrow line. This is a classic Sporadic-E footprint. The furthest station was GW7SMV at just over 4300kms.

4) Poland... The other unusual dimension to this opening was the unusual opening at the same time from Portugal to Poland. See the QSO map below from Tom, SP5MXU...

As you can see, SP5XMU was able to work stations in Portugal at a distance of almost 2800kms. What is unusual about this is that the usual maximum distance for one-hop Sporadic-E is about 2300kms. Where did the extra 500kms come from?

This is usually explained by say a tropo extension at one or both ends. Another is the possibility of chordal hop as suggested by SO3Z in the comments. In that scenario, the signal is going between two Sporadic-E clouds before returning to the ground again.

The chordal hop theory may help explain how the 144 MHz signals covered at least part of the 5600km distance from Cape Verde Islands to Poland.

Part 2 Conclusion... In the past with traditional modes like SSB and CW, we could be reasonably sure about the mode of propagation on VHF bands like 2 metres. Now with digital modes like FT8 we are seeing signals buried in the noise which makes it harder to be certain about how the signal was propagated.

I know FT8 isn't popular with everyone but the new digital modes are allowing radio amateurs to discover paths on VHF that we never knew existed.

* * * * *

Equivalent Distances... As always, it's interesting to look at some maps to put these remarkable distances in perspective.

The 5600 km distance from the Cape Verde Islands to Warsaw would reach as far north as Oslo, the capital of Norway.

It's hard to believe but the whole island of Iceland is actually closer!

From a western perspective, the equivalent distance reaches as far as Washington DC in the USA.

Remember, there are no satellites or moonbounce involved here. This is a 144 MHz signal being propagated by Sporadic-E and tropo.

What if...??? The map of the USA above suggests maybe one potential extraordinary path. From time to time, there seems to be a tropo duct across the Atlantic from Care Verde to the the Caribbean. Could this be extended even further to the west by a Sporadic-E opening at the same time???

FT8 signals heard by D4VHF...(over 3400kms)

Historic first Trans-Atlantic contact made on 432 MHz - Tues 7th April 2020

On Tuesday the 7th of April 2020, a remarkable contact was made with the FT8 digital mode on 432 MHz between D4VHF on the Cape Verde Islands off the coast of Africa and FG8OJ in Guadeloupe in the Caribbean.

This was the first 70cms trans-Atlantic contact without using satellites or the moon. The most likely mode of propagation was marine ducting with the signal being trapped close to the ocean.

* * * * *

Update: Saturday 11th April 2020 - D4VHF in Cape Verde and WP3ND in Puerto Rico complete a contact with FT8 on 432 MHz. This extends the trans-Atlantic distance to approx 4,367 kms. Full info further down this post.

* * * * *

(Make sure to scroll down for updates)

Trans-Atlantic Opening on 144 MHz from Cape Verde Islands to the Caribbean - Apr 2020

The trans-Atlantic path from Cape Verde Islands to the Caribbean on the 144 MHz band opened on Sunday the 5th of April 2020 and closed on Sunday the 12th of April 2020.

Ongoing reports below...

Details about the trans-Atlantic 432 MHz contacts are in a separate post.

* * * * *

Sunday 5th April 2020:

Breaking news! The FT8 signal from the D41VHF station in the Cape Verde Islands off the coast of Africa has just been reported in Martinique in the Caribbean on 144 MHz!

Screen showing FM4SA receiving the FT8 signal of D4VHF

The distance is approximately 3,864 kms.

Scroll down for updates...

144 MHz Trans-Atlantic record extended to almost 4,760kms!

The incredible tropo conditions between Cape Verde Islands and the Caribbean continue to amaze with trans-Atlantic contacts on 144 MHz and 432 MHz being made.

On Wednesday the 8th of April 2020, D4VHF in the Cape Verde Islands managed to work PJ2BR on Curacao on 144 MHz using the FT8 digital mode.

The distance was approximately 4,759 kms which is roughly 300 kms further than the previous trans-Atlantic record of 4,460 kms between D41CV and NP4BM on Puerto Rico in June of 2019.

The new 2m trans-Atlantic record distance was just 10 kms or so short of the IARU Region-1 144 MHz tropo record of 4,769 kms.

The map below shows the limit of the current IARU Region-1 record...

Update: Friday 10th April 2020 - It looks like conditions on the trans-Atlantic path improved to the point where a SSB contact was possible. While you watch the video below, remember that the distance is over 4,700kms. The distance across the North Atlantic from Newfoundland to Ireland is 3,000kms.

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New 432 MHz station on Cape Verde Islands raises possibility of new records being set

144 & 432 MHz Yagi antennas on Cape Verde

So far in 2019, the D4C contest team on Cape Verde Islands off the west coast of Africa have made some pretty amazing contacts on 144 MHz. Using the call D41CV, they have worked across the Atlantic to the Caribbean, up to the UK, France and Ireland via marine tropo ducting and into Germany, Italy and Slovenia with a combined Sporadic-E / marine ducting mode.

Many of these contacts were well in excess of 4000 kms in distance. See links to posts HERE.

The D4C team have recently announced that they are now active on 432 MHz (70cms).

"We are now capable to be active on #70cm #432Mhz #uhf using a 16 El yagi "Pinocchio" model (wooden boom) home made. Transverter connected to @FlexRadioSystem 6600M driving a solid state PA running 100W seems working as we have worked on SSB loc IM66 for 3000 km dx #hamradio"

As the tropo prediction map from F5LEN shows below, a marine duct off the west coast of Africa seems to exist for long periods of time during the Summer and Autumn months.

This should allow D41CV on the Cape Verde Islands to work up to coastal stations in Spain and Portugal on 432 MHz, a distance of roughly 2,900 kms.

Potential for new records???

Before we look at the potential of D41CV setting new records, we should probably look first at what the current IARU Region 1 record for tropo on 432 MHz is.

Back on the 9th of July 2015, G4LOH in the south-west of England worked D44TS on 432 MHz CW. This was a sea path of roughly 4070 kms, an amazing distance for 70 cms.

This contact was as a result of the marine duct extending much further north so that it managed to get as far as England.

Just to show how good conditions were that day, here is video clip showing G4LOH hearing the D4C/B beacon on 432 MHz...



One important point here is that G4LOH worked D44TS where as D41CV is actually on a different island. As you can seen from the map below, Cape Verde is spread out over several different islands...

You'll also notice that D41CV is further south than D44TS.

If we now look at how far 4070 kms is from D41CV then we get this map...

This means that if anyone in Ireland, Wales or England managed to work D41CV on 432 MHz then it would be a new IARU Region 1 tropo record.

I would suggest that as long as there is a 432 MHz capable station active on Cape Verde Islands then this is probably a case of 'when' rather than 'if '.

Trans-Atlantic on 432 MHz???

It's hard to imagine a 70cms signal getting across the Atlantic but it's something that can't be discounted.

Earlier in June of 2019, there was a tropo duct across the Atlantic from Cape Verde to the Caribbean which lasted several days and allowed the propagation of 144 MHz signals.

If 144 MHz signals lasted for several days, was there a shorter period of time when 432 MHz signals would have propagated inside the marine duct?

If it were possible then this is what the 4070 km distance from D41CV looks like...

If a 432 MHz signal can travel 4070 kms from Cape Verde Islands to England then perhaps trans-Atlantic is not impossible?

There should be some interesting times in the months and years ahead as these possibilities are explored.

Links...
1) Archive from G4LOH's blog
2) IARU Region 1 tropo records for 432 MHz
3) F5LEN Tropo Forecast

Remarkable opening on 144 MHz from Cape Verde Islands to Germany - 23rd July 2019

On Tuesday the 23rd of July 2019, there was another remarkable opening on 144 MHz from Cape Verde Islands off the west coast of Africa to Germany, Netherlands, Belgium and France in Europe.

This is the third such opening this year on 144 MHz where there has been a maritime tropo duct from Cape Verde Islands up to the south-west coast of the Iberian peninsula and then a Sporadic-E opening from that region.

The first such mixed propagation mode was back on the 9th of June 2019 to Italy, Slovenia and Austria. The second was on the 3rd of July 2019 when three stations in Germany heard D41CV.

What was significant for the third opening however was that there was a successful FT8 contact made with DK5AI in Germany, an amazing distance of 4966 kms.

The map above shows the stations that were heard by or had heard D41CV on FT8 on 144 MHz.

While the tropo duct off the coast of Africa was probably stable, the Sporadic-E opening up into Europe seems to have come in two distinct phases.

The four German stations were around 15:08 to 15:40 UTC. The other signals were around 16:34 to 17:40 UTC.

Update : This is the log of FT8 contacts made by D41CV on the 23rd of July. Red contacts are Sp-E + tropo. Black is tropo only...

This is a screen shot of the FT8 contact between D41CV and DK5AI...

This is the tropo prediction map from F5LEN showing the maritime tropo duct up along the west coast of Africa.

Considering this is the third such opening this ear, it might be easy to take it for granted but we shouldn't. A distance of 4,966 kms on 144 MHz is really incredible.

Just for fun, lets suppose that DK5AI was able to work that distance across the Atlantic. This is how far his signal would reach...

The future...5000+ kms??... It's very likely that we haven't seen the maximum distance yet for this mixed propagation path. The marine duct off the west coast of Africa seems to exist for long periods of time so that is a significant factor. The big variable is of course the requirement for a Sporadic-E opening on 144 MHz to complete the path.

Stations in the north of Germany near Hamburg or in Denmark may well be within one Sp-E hop of the coast of Portugal. If this coincided with a marine duct to Cape Verde, contacts in the region of 5,200 kms may be possible.

Links...
1) D4C contest team on Twitter
2) F5LEN Tropo prediction for D4

G3SMT works Cape Verde Islands to set new 144 MHz Tropo record

Back on the 5th of August 2018, Mark Turner EI3KD worked D4Z in the Cape Verde Islands off the coast of Africa to set a new IARU Region 1 tropo record on 144 MHz. Now less than two months later, that record has been broken again.

On Tuesday the 25th of September 2018, the marine duct from the Cape Verde Islands expended as far north as the British and Irish Isles again.

At 21:10, EI3KD managed to repeat his record distance by working D4Z on cw for a second time, a distance of 4163 kms.

At approx 21:46, GW0KZG in IO71LW in the west of Wales worked D4Z to extend the record to approx 4270 kms. It turned out to be one of the shortest held records however,

At approx 21:47, Peter Torrry G3SMT worked D4Z (HK76MU) to set a new IARU 144 MHz Region 1 record of 4431 kms. Peter's locator square is IO82KV.

DX-Cluster spots - 25th Sept 2018...
GW0KZG 144300.0 D4Z 22:12 25 Sep IO71LW HK76MU still 519 cal Cape Verde
G3SMT 144300.0 D4Z 21:46 25 Sep IO82KV HK76MU Cape Verde
GW0KZG 144300.0 D4Z 21:45 25 Sep IO71LW HK76MU 539 tks QSO Cape Verde
G7RAU 144300.0 D4Z 21:42 25 Sep IN79JX HK76MU 599+ cq, gl Cape Verde
G7RAU 144300.0 D4Z 21:18 25 Sep IN79JX HK76MU 559! wow! Cape Verde
EI3KD 144300.0 D4Z 21:11 25 Sep IO51VW HK76MU tnx! 589 cq Cape Verde

D41CV was also worked on FT8...
M0BUL-@ 144174.0 D41CV 22:28 25 Sep tnx Cape Verde
GW0KZG 144174.0 D41CV 22:27 25 Sep IO71LWHK76TC H-10,/-04 Tn Cape Verde
EI3KD 144174.0 D41CV 22:22 25 Sep IO51VW HK76MU oops call :) Cape Verde
G7RAU 144174.0 D41CV 22:19 25 Sep IN79JX HK76MU +03 FT8 GL! Cape Verde

This is the tropo prediction map for the path at the time...

Source : F5LEN

It's probably likely that the record will be extended again at some stage in the future with perhaps a contact to Northern Ireland or Scotland.

Just to illustrate just how far the G3SMT - D44Z contact was, this is the equivalent distance across the Atlantic from the south-west coast of Ireland.

Links...
1) F5LEN Tropo prediction map
2) ON4KST Chat
3) Post on D4C website