E-mail to Peter, SM2CEW in Luleå KP15cr, 13 March, 2021
Yesterday I noticed on the DX-cluster that SM7GVF (JO77ga) 18:03 UTC had an aurora QSO on 144 MHz with RA1AMW (KP40um) and SM4HMI (JP70to) with same station 17 minutes later. Listened on 144 MHz but heard nothing. Also listened on 50 MHz with a vertical but didn´t hear anything.
Later noticed that SM2A in Skellefteå (KP04np) 18:37 UTC heard the beacon JW7SIX on Svalbard (JP68tb) on 50.447 MHz with his comment "AUE VY QSB".
Listened again on 50 MHz 21:19 UTC and heard JW7SIX. Signals were VY QSB! Thought for a while that it was meteor scatter, space garbage or missile rain over the Arctic Ocean :-) This can probably be ruled out and also aircraft scatter.
Never heard JW7SIX with such QSB signals. They are usually long time stable signals. Have you heard anything like "VY QSB" before ??? Any explanation?
JW7SIX transmits with 10 W to a 3 element horizontal yagi facing south. Note, I used a vertical antenna. It is a fairly long distance, just over 1300 km, to my QTH in Boden (KP05vs). The wave propagation is not an ordinary aurora reflection with backscatter. So something else is happening in the ionosphere.
Peter answered:
Glad you heard JW7SIX so well. As I see it, this is classic sporadic E but it is created by strong aurora. Signals are present during a strong aurora, not after.
Some like to call it AuE (Auroral E), but in my world this is something different. With AuE signals are weaker and stable at that weak level and the propagation mode occurs after an aurora event.
AuE generally doesn’t produce full reflection with very strong signals like the more common sporadic E does where signals are very strong over these distances.
Often when listening to JW7SIX and JW5SIX (on 50.445 MHz) the strength varies enormously, just as you’ve noted. Especially when the aurora is south of us which it was last night. In this situation there will not be a stable sporadic E between us and Svalbard, so there is a lot of QSB.
However, the beacon signals can be very stable for a long time when the aurora is above or north of us. At those times these beacons usually send my S-meter to full deflection on peaks, but with QSB of course.
In about 70% of cases, JW7SIX is very loud via sporadic E while JW5SIX is just down in the noise or not heard at all. On occasion, but this is highly unusual, I have heard JW5SIX only and not JW7SIX. Even though they are not far from each other, the distance between them is enough to give different results when there is sporadic E.
The polarization is most likely rather irrelevant for sporadic E. With tropo signals it’s the opposite - polarization matters a lot.
On shortwave, signals via the ionosphere, are basically heard just as well regardless of polarization. But of course, the radiation angle from the receive antenna plays a role when comparing signal strength. So it is not always easy to determine which antenna is best in all cases, instead it might differ quite a lot depending on the incoming angle of the received signal. You just can’t have too many antennas ...
Our beacon SL2ZZU (KP15co) in Luleå on 50.492 MHz runs low power to a vertical and and is heard well over northern Europe when via sporadic E.
What I would want to refer to as AuE is a type of propagation that is in many ways is similar to ionoscatter. But it occurs AFTER a strong aurora. The signals are weak but stable. I have made a lot of QSOs over the years on 144 MHz via AuE. It is indeed forward scatter, direct path, as opposed to aurora scatter where you normally beam offset to the real heading.
This propagation mode is more common during the summer and preferably during, or close to, solar maximum. Again, the phenomenon always occurs after a strong aurora event. Via AuE on 144 MHz more or less all of the stations worked have been to the south of me – in SM7, OZ, LA, DL, G, PA, ON. Some QSOs over pretty long distances. TF Iceland, due west, has also been worked by me via AuE.
In the 80´s and 90´s UA1ZCL had a 144 MHz beacon running in Murmansk. The power was 300 watts RF to two yagis beaming south-west. It was an absolutely phenomenal beacon to help us discover AuE on 144 MHz. The UA1ZCL beacon was frequently reported in SM7, OZ, northern DL and probably also G/GM.
The same was true with the beacon SK2VHG in Kiruna (Esrange), also running fairly high power and beaming south. A perfect beacon to help us detect AuE on 144 MHz.
In the late 80’s and during the 90’s there were a lot of VHF expeditions by people from SM, LA, OZ, DL, PA etc who went on meteor scatter expeditions to the northernmost squares in Scandinavia. Their main target was to work others via meteorscatter. On many occasions they became particularly surprised to suddenly hear their opposite stations faintly all the time and not via meteors.
In general this was via AuE after a strong aurora event. But also on occasion via ionoscatter with no aurora present. Ionoscatter is particularly good during the early part of summer when the mesosphere is at it’s lowest temperature and better supports refraktion of VHF signals.
As we’ve said to each other so many times - propagation on VHF in the Arctic region is a really interesting topic and we are still learning every day!! But we need beacons and activity on the bands to detect these openings.
On June 25, 2018 I heard the Greenland beacon OX6M on 50.047 MHz. And Peter worked OX3XR. Info with video here:
http://sm0fobradio.blogspot.com/2018/06/sporadiskt-e-50-mhz-gronland.html