Propagation News – 25 September 2016

This week saw the solar flux index increase from 80 to 86, but poor ionospheric conditions due to a high-speed solar wind stream dominated the earlier part of the week. The K-index hit five on the 20th but, as predicted, geomagnetic conditions improved slightly towards the end of the week.

On the bright side, while some days have seen very poor HF conditions, there have been highlights. The Chilton ionosonde has indicated that the maximum usable frequency over a 3,000km path has exceeded 21MHz at times. And better autumnal conditions mean that there is DX around. This is an ideal month for working South Africa and South America on 18, 21 and even 24MHz at times.

East-west paths may be better on 14MHz, and will improve as we head into October. And don’t ignore 30m at the moment, which may deliver some surprises. Eighty and 40 metres are also starting to come into their own at dusk and after sunset.

Our best advice is look for days that are geomagnetically quiet. That is, when the K-index is zero, one or two. This may be tricky as NOAA predicts very unsettled geomagnetic conditions for eight days from September 28th. So work your best DX in the first half of this week.

VHF and up propagation

Prospects for tropospheric openings are poor this week, with low pressure near to the north and west of Britain bringing autumnal weather. For much of the period this will mean some quite strong winds at times and little chance of tropo developing. There may be some rain scatter options, although this could be difficult with fast-moving weather systems.

There is likely to be high pressure over the continent and this will place the better tropo conditions over the near continent and across Biscay at times, and probably not accessible for most of the country. The sporadic E season seems to be over, so it’s back to random meteor scatter as the main DX mode on the lower VHF bands.

Moon declination is heading negative again later this week so EME moon windows will shorten as the week goes on. Losses are also increasing as the moon heads out to apogee. But don’t despair of the poor VHF conditions. There are plenty of workable satellites in orbit to give you your fix of VHF DX, so why not give them a try? Go to the AMSAT-UK website for information.

Category: GB2RS Propagation News