As the Summer Sporadic-E season begins in the southern hemisphere, there have been reports of openings on the 50 MHz and 144 MHz bands.
In Australia, there is a very active community of stations using WSPR beacon mode on the 2m and 6m bands with a lot of success. On the 9th of December, the 144 MHz WSPR signal from VK2IJM near Sydney was heard almost 3200 kms away on the island of Fiji by 3D2TS.
UTC (y-m-d) TX txGrid RX rxGrid MHz W SNR drift km
2021-12-09 23:08 VK2IJM QF56ni 3D2TS RH91fv 144.490586 20 -29 -1 3218
2021-12-09 23:08 VK2IJM QF56ni 3D2TS RH91fv 144.490586 20 -29 -1 3218
As you can see from the single reception report, the signal was -29dB which is an incredibly weak signal.
The two stations tried to complete a FT8 contact just 14 minutes later. 3D2TS on Fuji could hear VK2IJM at-21dB but 3D2TS wasn't strong enough in Australia to complete a contact.
Propagation Mode???... The next question is how did a 144 MHz signal get from Sydney to Fiji? The maximum distance for one hop Sporadic-E is about 2300kms so something else has to account for the additional 900kms.
It's probably no accident that this happened over a sea path and the most likely explanation is a combined one hop Sporadic-E signal that coupled into a marine duct over the ocean. The above tropo forecast map from Pascal, F5LEN certainly supports this theory.
It's not possible to completely rule out a 100% marine duct or a chordal hop Sporadic-E opening with two Sp-E clouds but the highest probability is a combined Sp-E / tropo duct.
Links...
1) Check out my 144 MHz page for details of more 3000km+ openings.
Just a small correction, the distance was 3218Km, so 200km further than you mention above.
ReplyDeleteIn terms of the propagation mode, I think it was either one hop from AU to the mid-point and then marine ducting for the second leg of the path or a chordal double hop. The intense Es on 6m alerted us to try 2m and thus this spot resulted and 3 FT8 spots were also reported (all one way).
Regards John, VK2IJM