Almost but not quite: On the 5th of June 2021, Stamen LZ1KU in Bulgaria and Oleg A65BR in the United Arab Emirates almost managed to complete a FT8 contact on 144 MHz over a distance of 3,280kms.
While both stations managed to get some successful decodes, they were unable to complete a contact on this occasion.
The composite screen above from LZ1KU shows a decoded FT8 signal from A65BR at -20dB. An earlier decode at 14:48 UTC was at -16dB. The exchange shows A65BR giving a signal of -13dB for LZ1KU.
2021-06-05 14:48:58Z LZ1KU Stamen FT8 144445 -16 dB 0.3 s Freq 1369 Hz > CQ A65BR LL75
In the examples above, the FT8 signal would have been below what is really audible to the human ear so a contact on CW would have been very unlikely.
A65BR also spotted LZ1KU on the DX-Cluster...
A65BR 144174 LZ1KU 14:37 05 Jun 21 LL75SL<ES>KN32AH CQ HRD Bulgaria
LZ1KU was reported to be using 'full power' to 4 x 12-element Yagi array while A65BR was using 50-watts to a 7-element.
Amazingly, IZ7AUH in the south of Italy also managed to get a decode from A65BR over a distance of almost 3,900kms.
Propagation Mode: Both paths were well in excess of the 2300kms or so we might expect from one hop Sporadic-E so how can we explain it?
The tropo prediction map from Pascal, F5LEN shows some excellent conditions in the Arabian Gulf so it is probably no great suprise that the 3000km+ paths were in that direction.
One scenario is that there was a tropo duct over the Arabian Sea and this then coupled into a single hop Sporadic-E opening to Bulgaria. For the Italian station, it would require another few hundred kms of tropo at the western end of the circuit to complete the path.
Another scenario was that it was Chordal Hop Sporadic-E with the 144 MHz signal bouncing off two Sp-E clouds that were in just the right location. There was an extensive Sporadic-E opening from Israel into Europe so the MUF was high in the region.
And just to add another variable into the mix, the International Space Station was around at the same time (or at least I think it was based on an observer in Ankara).
It's hard to know for sure what the exact propagation mode was. It's a bit like a science experiment and we have just two data points. It's easy to make assumptions but we just don't know.
For me, the main thing is that it is yet another example of a 3000km+ path on the 144 MHz band.
