On the 28th of May 2025, there was a Sporadic-E opening in Europe on the 144 MHz band. While single hop Sporadic-E openings are of interest to the individuals concerned, the interesting paths are the really long distance ones that can't be so easily explained.
The maximum distance for one hop Sporadic-E is about 2300kms although this can be extended somewhat at either end by tropo. The paths shown above are for those that are over 2800kms with eight over the 3000km mark.
It's very likely that these were double hop Sporadic-E. This requires two separate areas in the E-layer of the ionosphere which support propagation at 144 MHz. One area is unusual but it's a lot rarer to get two areas at the correct distance apart at the same time.
The list of stations over 2700kms is shown below...
2025-05-28 15:46:00 G4PEM (IO70IE) 144.176 FT8 RY6N (KN97VG) 3270 IO70ie KN97 FT8 +11
2025-05-28 15:47:00 RY6N (KN97VG) 144.176 FT8 G4LOH (IO70JC) 3266 KN97vg IO70 FT8 +20
2025-05-28 15:50:09 G4RRA (IO80BS) 144.174 FT8 RY6N (KN97VG) 3159 IO80BS ES KN97VG
2025-05-28 15:52:39 G4RRA (IO80BS) 144.174 FT8 UA6LJV (KN97LE) 3105 IO80BS ES KN97LE seen
2025-05-28 15:58:33 F6DBI (IN88IJ) 144.174 FT8 RN3QR (LO00BK) 3102 IN88IJ ES LO00BK TKS
2025-05-28 15:56:00 F6EGD (IN88HR) 144.175 FT8 RN3QR (LO00BK) 3095 IN88hr LO00 FT8 -12
2025-05-28 15:52:03 GW7SMV (IO81LO) 144.174 FT8 R6CS (KN95BW) 3038 ES FT8 +0 dB 2165 Hz hrd
2025-05-28 15:49:52 G4RRA (IO80BS) 144.174 FT8 R6OH (KN97CW) 3021 IO80BS ES KN97CW
2025-05-28 15:52:07 G4RRA (IO80BS) 144.174 FT8 RA6O (KN87UX) 2985 IO80BS ES KN87UX seen
2025-05-28 15:53:00 UR7IMM (KN88TR) 144.175 FT8 F6EGD (IN88HR) 2969 KN88tr IN88 FT8 -18
2025-05-28 15:46:00 RY6N (KN97VG) 144.175 FT8 M0CFO (IO90) 2961 KN97vg IO90 FT8 -02
2025-05-28 15:46:14 G4DCV (IO91OF) 144.174 FT8 RY6N (KN97VG) 2938 IO91 ES KN97 73
2025-05-28 15:54:54 F6DBI (IN88IJ) 144.174 FT8 UT7LK (KN89BW) 2836 IN88IJ ES KN89BW TKS
2025-05-28 15:56:10 G4RRA (IO80BS) 144.174 FT8 US5EII (KN78JK) 2765 IO80BS ES KN78JK seen
Propagation Mode?... While it seems likely that there were two hops involved, it's open to debate whether the signals bounced off the ground mid-path or whether there was some chordal hop as shown in the example above.
Trans-Atlantic?... The distance from Ireland to Newfoundland is about 3000kms. Looking at the distance of the East-West paths on the 28th of May, the question is if a similar path might exist at times on 144 MHz across the North Atlantic?
Link... For more examples of long distance 2m paths, see my 144 MHz page.
Addendum:
1kW into 4 x 16ele
Log:
15:42 RY6N KN97vg 3270km
15:45 R6OH KN97cw 3132km
15:46 RA6O KN87ux 3095km
15:46 US5EII KN78jk 2876km
15:47 RK6MF KN97rc 3253km
15:48 RK7N KN97kg 3206km
15:49 UA6LJV KN97le 3215km
15:50 UR7IMM KN88tr 3061km
16:10 SP8WW KN19fm
16:12 SP8WJW KN09sr
Comment: An interesting chordal hop opening. I saw 3 stations in Russia and 5 others in Eastern Ukraine, followed by two more in South East Poland, all FT8. One complete QSO, the others were heard loud for ~10 minutes, pure chordal hop. The SP stations were seen a few minutes after the chordal opening ended.
To be fair and just an observation, it is probably worth noting that these are not your standard 100watts contacts, but more 1KW into either large or stacked antennas.
ReplyDeleteFor me, I'd like to see a breakdown of each station to actually understand what can be achieved with a QRO station on 144Mhz.
The propagation mode for this event is almost certainly chordal e-s without any tropo extension.
ReplyDeleteReference to Live MuF maps and Hepburn/F5LEN predictions at the time of the contacts quite clearly shows what was happening. There were many of those who understand waiting for it to happen! The MuF was high in two places causing significant refraction of 144MHz signals which for some stations happened to perfectly align.
As to the previous comment about stacked arrays; nonsense, many of those gaining contacts only used one Yagi. Please see my comments below. However, 500-1000W certainly helps when signals are weak such as they often are in chordal e-s events as losses can be quite high.
The age-old HF concept of ground reflection just does not happen at 144MHz. Most of the planet is far too rough and any reflection will he highly scattered and lossy. VHF propagation texts need to be re-written to cut out such simple, antique HF ideas!
There are many such instances of such propagation on 144MHz and those that use the right tools are always on the look-out for such events.
Having stacked antennas does not necessarily help as you can often have a take-off angle too low for the propagation. If you take a look at my QRZ.com pages (G4SWX) you will see what 'too big' for many sporadic-e events means.
https://www.qrz.com/db/G4SWX
With sloping ground to the East my take off angle is around 1.3 degrees. Signals coming in at much higher elevations with be strong with my locals but not me!.
Where stacked arrays do help is where you are located beyond the area where signals are at their strongest. My large array enables me to participate in 144MHz events which are strong in PA & DL and are not heard by most in the UK.
The 'interesting' paths can almost always be easily explained as can 144MHz ionoscatter events, up to about 2000Km at this time of year. Please see Tim Fern G4LOH's explanation of this in a DUBUS article last year.
John G4SWX