Back on the 3rd of July, there was some excellent Sporadic-E propogation over Europe with some very impressive distances. One of those contacts was between Tom, EI4DQ (IO51wu) and SV9CVY (KM25ka) on the island of Crete, a distance of about 3,213 kms. Anyone that knows about Sporadic-E will know that the usual maximum distance for 1 hop is around 2,300 kms so the above distance is unusual. (On the map above, 2300 kms would be roughly from EI4DQ to roughly the heel of Italy).
Now, there are probably 3 possible explanations for this type of contact...
1) Double hop Sporadic-E as shown above...using clouds #2 and #3
2) Chordal hop where the Sporadic-E clouds may be slightly tilted and the signal goes from cloud to cloud rather than bouncing off the ground in the middle.......i.e. the signal goes directly from cloud #2 to cloud #3.
3) There was an extension at either end or both ends due to tropospheric propogation.
Considering that the MUF does not reach as high as 144 MHz that often, it's remarkable that it should happen in 2 spots at once. Hence, that's why these type of contacts are pretty rare.
Now for a bit of fun ;o)......what happens if we take that 3,213 km contact and plot it from EI4DQ's location in the opposite direction...
Now, there's a big difference between the path from EI to SV9 compared to the path from EI to VO (Newfoundland). For one thing, EI to VO is a lot further North and Newfoundland is a lot closer to the magnetic North pole, all factors which seem to reduce the chances of there being suitable Sporadic-E.
It does however raise the question of whether it is possible? Europe to North America direct on 144 MHz.......can it be done???