Propagation News – 4 December 2017

Last week was a mixed bag in terms of HF propagation. The solar flux index hovered around the 80 mark and the K-index was poor at the weekend, although a little more settled later in the week.

Last weekend saw the CW leg of CQ Worldwide and the consensus was that conditions weren’t brilliant. We said that 20 and 15m would be the optimum HF bands with occasional 10m openings. This turned out to be true as Roger, G3LDI proved by only working 67 stations on 10 metres in 48 hours. Roger said that they were mostly weak and watery European contacts, despite using a three-element SteppIR. The days of extensive DX openings on 10m may, alas, be behind us for a few years.

Back to the Sun, there have been three visible sunspot groups, with region 2615 generating M-class solar flares. So watch out for potential coronal mass ejections and flare-induced blackouts or sudden ionospheric disturbances.

As we head into December, now is the best time for the low bands, especially Top Band and 80m. You may find that the evening critical frequency drops so much that 40m struggles to open to DX at times. With a typical critical frequency of around 3MHz at 2000hrs even 80m may struggle at distances less than 300-400km. Unfortunately, geomagnetic conditions are also predicted to be unsettled from December 7th to the 11th due to recurrent coronal hole effects.

VHF and up propagation

High pressure will continue to provide slightly improved tropo conditions on the VHF/UHF bands at the beginning of the week, but there is likely to be a slow decline later as pressure falls to the north of Britain. Although lift conditions could affect much of the country at first, these will become confined to the south by midweek and all gone soon after.

Don’t forget to try the multimode part of the bands with CW or SSB, and do call CQ and announce your activity in advance on email reflectors, DX chat such as ON4KST.info and social media if the bands seem quiet.

The Moon is at lowest declination today and path losses are still high, but declination goes positive late on Thursday 8th and losses are lower. Look out for GHz bands EME operation from Jericho from that day until 13 December by E44QX and E44HP.

The big Geminids meteor shower is now only a week away. The zenithal hourly rate for this shower is up to 120 meteors per hour, so it’s a really good one. We’ll have more information next week as to the best times to operate. Look at dl1dbc.net for Virgo, a Java real-time meteor tracking web page that may help you. Unfortunately it doesn’t run on all browsers: you may have to try more than one before you get it to work.

Category: GB2RS Propagation News