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.

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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

Looking back at the first 144 MHz trans-Atlantic reception report of the Cape Verde D4C beacon in 2015

In a previous post, I reported on the first ever trans-Atlantic contact between the Canary Islands and the Caribbean on 144 MHz. As with many other posts, this generated some discussion online and I was interested to read that the first 144 MHz trans-Atlantic report to the Caribbean was back in 2015 by PJ4VHF.

To be honest, I can't remember seeing this before and it's possible that I did read it but forgot about it. As I keep a record of the 2m trans-Atlantic openings on my 144 MHz page, I thought it only right that I should do up a post about it and have a record of it here on the site.

Dave Pederson, N7BHC operated from the island of Bonaire in the Caribbean as PJ4VHF from February 2012 to June 2019. While there, he operated on the 50 MHz, 144 MHz and 432 MHz bands.

The above photo shows the antennas used by PJ4VHF at about 12 metres above ground level...a 5 element Yagi on 50 MHz (M2 6M5X), a pair of stacked 13-element Yagis on 144 MHz (Cushcraft 13B2) and a 43 element Yagi on 432 MHz (M2 43-9WL).

On the evening of the 6th of May 2015, PJ4VHF heard the Cape Verde D4C beacon on CW on 144.436 MHz for about 90 minutes (01:00 to 02:30 UTC). The distance across the Atlantic was 4,694 kms (2,917 miles).

The D4C beacon was running 20 watts into a 5-element Yagi and the CW signal was reported as being 10dB out of the noise.

The video above shows the reception of the D4C beacon on the 6th of May 2015. The morse code message reads... D4C/B HK76MV     DE D4C/B HK76MV

The reception report was subsequently confirmed by QSL card...

From the ARRL News..... Pedersen, PJ4VHF/N7BHC, on Bonaire copied a 2 meter CW signal from the D4C/B beacon on 144.436 MHz at Cape Verde via tropospheric ducting on May 6 (0100-0230 UTC). Bonaire is in the Caribbean just north of Venezuela, while Cape Verde is off the coast of Africa, west of Senegal — a distance of nearly 3000 miles.

The D4C beacon runs 20 W and is about 750 meters above sea level. Pederson was able to confirm the transmission with the beacon operator, HB9DUR. He was using a Kenwood TS-2000 and two 13 element Yagis.

“I had parked my VHF array pointing west for minimum wind resistance,” Pederson told ARRL Propagation Contributing Editor Tad Cook, K7RA. “Tuesday evening [May 5] I was doing some paperwork in the shack and rotated the beams back east at 0100 UTC to prepare for listening all night. To my amazement, I started copying CW while the beam was still 30° off the D4C bearing.”

D4C contest site on top of a mountain on the Cape Verde Islands

Later in June of 2015, NP2X received signals from a German ham visiting Cape Verde one night, and a couple of nights later he was heard by the German visitor on D4, but unfortunately no two-way contact was made.

At the time in 2015, the D4C contest site was unmanned for most of the time but in later years remote operation become possible. The reception report by PJ4VHF showed that a trans-Atlantic sea path by tropo on 144 MHz was possible and this encouraged others to make the effort.

The first trans-Atlantic contact on 144 MHz between Cape Verde and the Caribbean took place four years later in June of 2019.

More details about the various trans-Atlantic contacts on 144 MHz can be found here... https://ei7gl.blogspot.com/p/144-mhz.html

Externals links...

1) ARRL News item
2) PJ4VHF website

3) Report on the D4C website