VHF propagation in Northern Scandinavia

North of the Arctic Circle, the VHF propagation situation is probably very different from what most other VHF amateurs in Central Europe are used to. During contests the 144 MHz activity is zero and long distance tropospheric ducting does not occur due to the high mountains.

Aurora is possible though, and has been observed by others, but is really rare at latitudes above 67 degrees north.

Sporadic-E with its strong and stable signals is easy to recognize, but on 144 MHz even more seldom at northern latitudes. Years ago some British amateurs were monitored in Tromsø (JP99LP) with hand-held transceivers in FM, and in May 1991 the LA7VHF beacon was copied by DK1KO for 30 minutes with a solid 579 signal. LA1MFA in JP99 has worked into Southern Sweden once. On 50 MHz the chances for contacts via Sporadic-E are good during the summer months, even late at night.

A hybrid mode, among amateurs usually called Aurora-E, seems to be very frequent between May and August, peaking in June and July. Because of the at least on 144 MHz significant signal audio characteristics and diurnal variation of observation it is suspected that Aurora-E is identical with what scientists call Polar-Mesosphere-Summer-Echos (PMSE). Although several research programmes have been executed, the phenomenon is still not understood in all details. Aurora-E is one of the few remaining subjects where amateur observations may well contribute to ionospheric science. The amount and distribution of possible monitoring stations is large compared to scientific installations and reports from radio amateurs would certainly help to improve statistics.

UA1ZCL near Murmansk has frequently worked via Aurora-E down to Denmark and Northern Germany, and also LA0BY has made many contacts. The propagation seems to occur often before, during or after periods of strong Aurora from 06-10 UT and 20-00 UT, but openings in the early afternoon have also been noticed. Probably caused by reflection on rapidly moving thin sloping layers at heights around 85 km, the signal shows rapid fading and often appears weak, even though the fieldstrengths may be quite reasonable. The position of the reflective layers may follow that of the auroral oval. A location above Oslo at 58 degrees North will allow for contacts between Northern Scandinavia and Central Europe.