venerdì 11 novembre 2016

Propagation News – 13 November 2016

Last week saw DX being worked on HF as more-settled geomagnetic conditions allowed the ionosphere to strengthen. There were reports of US stations being worked on 40m before midnight, and DX contacts on 20m, 17m and 15m across the globe.

The solar flux index remained in the high 70s, and the geomagnetic K index remained mostly at one or two. This resulted in a settled ionosphere that saw daytime critical frequencies rise to 7.1MHz in the early afternoon, and maximum usable frequencies over a 3,000km path climb to more than 25MHz.

Unfortunately, the good conditions couldn’t last and NOAA issued a geomagnetic storm alert due to a high-speed solar wind stream from a recurrent, negative-polarity coronal hole. By the evening of Thursday the 10th, the K index had risen to four.

Next week the solar flux index should remain in the 70s/80s, but this weekend will be dominated by poor geomagnetic conditions, with lower maximum usable frequencies, noisier bands, and an increased chance of auroral conditions.

Geomagnetic conditions should improve around the 16th and hopefully bring better propagation, at least until the weekend of the 19th and 20th when coronal hole effects may kick in again. You can get an initial positive propagation phase when solar plasma first hits so watch the HF bands as the K index first starts to rise.

It’s going to be another week of hard work to get much Tropo from the VHF/UHF bands. However, there is likely to be a weak ridge over northern France and southern Britain on Sunday and Monday, which will slowly decline thereafter. So if there is anything worthwhile, it looks like the southern half of the country and into northern France, the Low Countries and Germany offer the best Tropo options for the first half of the week.

The northern half of Britain will remain closer to low pressure and more unstable showery air, so unlikely to benefit from any Tropo enhancements this week.

Don’t forget that with a Yagi and a bit of power you can always work DX up to 800km using aircraft scatter on the higher VHF/UHF bands.

For meteor scatter enthusiasts, Thursday sees the major shower for this month – the Leonids. It’s predicted to peak at around 10:30am so look out for enhanced conditions and an opportunity to try out the new MSK144 mode from K1JT’s WSJT-X 1.7 software.

Six metre activity on this mode seems to be on or around 50.280MHz

EME path losses are at their lowest at the moment with the Moon at perigee on Monday. Declination is at a maximum on Thursday, so, in all, a good week for EME.