Propagation News – 22 July 2018

Last weekend’s IARU contest saw a lot of action on the HF bands, which just goes to show that it isn’t all about sunspots. In fact, we have now gone more than three weeks without sunspots, which has been described as almost a decade-class event. The last time the sun lost its spots for 21 consecutive days was in 2009. So, the moral is to make the most of what we have in terms of ionospheric propagation on HF.

Next week, NOAA predicts more of the same, with the solar flux index starting at around 72 and declining to 68 as the week goes on. This weekend may be unsettled geomagnetically as the result of an equatorial coronal hole on the Sun. We have just had a run of settled conditions that have seen the critical frequency hover around the high 4MHz area, but never reaching 5MHz. As such, NVIS contacts around the UK during the day have been difficult.

Maximum useable frequencies over a 3,000km path this week are likely to remain in the 14-18MHz range. This is a pattern that we may see continue until the autumn.

VHF and up

We should be getting the hang of this high pressure pattern and the type of VHF conditions it brings by now. We have another week with similar characteristics coming up, so it’ll be no surprise to hear that tropo will feature quite a lot, but perhaps not so much in the far north where low pressure will be nearby at times.

As usual, the south-west of the UK down to Iberia will offer the best chance of DX. East coast stations should be able to take advantage of sea ducting over to the Continent.

There is a chance of one or two showers, so perhaps a glimmer of hope for some rain scatter. Failing that, it’ll be sporadic E that offers some excitement, although in recent days there’s been a weakness about it. This could be down to many things, including the placement and sparsity of weather triggers to generate the necessary turbulent wave motion that is part of the mechanism for making sporadic E. Let’s hope that next week offers some improvement, although it’s looking a bit marginal.

The Moon reaches minimum declination and apogee on Wednesday so Moon elevations will be very low and losses at their highest for EME. This is a week to try some satellite operation with a handheld antenna from the back garden or balcony!

Category: GB2RS Propagation News