venerdì 24 giugno 2016

Propagation News – 26 June 2016

Once again the sun looks pretty spotless, apart from one tiny smudge. As a result, this week saw the solar flux index drop below 80. We’re beginning to sound like a stuck record, but ongoing coronal hole activity pushed the K-index to five on Wednesday 22nd. Noisy electrical storms across most of northern Europe didn’t help the bands either.

Next week the USAF predicts the solar flux index will be in the range 70-80, with the potential for unsettled geomagnetic conditions on Saturday the 2nd and Sunday, 3 July. As the solar flux index at sunspot minimum doesn’t fall below about 66, this gives you some idea of the current state of the sun.

As it is mid-summer we can’t expect fantastic HF conditions either, with lower maximum usable frequencies during the day, compared with the autumn and winter, but higher MUFs at night.

If you want a challenge, try listening for the Alexanderson alternator at station SAQ in Grimeton, Sweden on 17.2kHz CW at 0900 and 1200UTC on Sunday, 3 July. The Twente SDR on the web can cover 17.2kHz, or you can hook an antenna up to your sound card and use some specialist software. Amateur station SK6SAQ will also be active on 80m SSB and 40, 20 and 15m CW during the day.

VHF and up propagation news:

Sporadic-E may be poorer next week as the main Atlantic jet stream activity has already migrated north, leaving much of central Europe under a much slacker pattern. The absence of active jet streams over Europe probably means that one of the main sporadic E triggers, gravity waves, may be missing or reduced. These waves propagate up from the turbulence of the jet stream at 12km height to the E region at 120km.

This absence will make sporadic E hard to come by except perhaps for the more northern paths across to Scandinavia where the jet stream may be slightly more active.

Next week we will find a big high with a very large east-west extent just north of the Azores and covering much of the Atlantic. This could give some interesting tropo paths down the western side of Europe from the UK to Spain and Portugal and onwards to the Canaries or Cape Verde.

It may also be a tempting week for those seeking the more unlikely options of transatlantic tropo. This is very much a long shot, since there are fronts involved which can easily break any ducts.

Moon declination goes positive on Monday and losses are falling with perigee on Friday, so EME conditions will improve as the week progresses.