Propagation News – 9 July 2017

| July 7, 2017

Earlier last week the sun’s surface looked clear. There were no sunspots at all and the solar flux index remained in the low 70s. However, settled geomagnetic conditions helped make up for this with the K-index often at zero.

Daytime D-layer absorption didn’t really help with the summer HF doldrums, but there were highlights in the evening with 40m and 20m becoming more lively as the sun started to set. For example, Doug, ZP6CW in Paraguay was workable with five watts CW on 20m on Wednesday evening and 40m was alive with signals from around Europe. The Reverse Beacon Network is often a guide to DX stations calling CQ, many of which go unanswered.

However, this weekend, the 8th and 9th, may see unsettled geomagnetic conditions again as a large coronal hole became geocentric on Thursday. This may allow solar material to escape from the Sun and head towards Earth. If so, the subsequent geomagnetic storming may see the K-index rise this weekend, with the possibility of an initial ionospheric enhancement and then subdued maximum useable frequencies, auroral conditions and noisy bands thereafter.

Next week, NOAA predicts the solar flux index will remain in the low 70s, although a new sunspot was just appearing over the south-east limb of the sun on Thursday. NOAA predicts geomagnetic conditions may be very unsettled again from Thursday the 13th.

The 20, 30 and 40m bands remain the best for F2-layer DX fun, with the HF bands also benefitting from occasional sporadic E openings. However, these may become slightly less prevalent as we move into mid and late July.

VHF and up

Humid weather with a weak ridge of high pressure can often bring some summer tropo conditions and this week will continue to offer occasional lifts, especially overnight.

There is a sign in the models for some slow-moving areas of low pressure during the week and these may bring a risk of thundery downpours, but equally the opportunity of some good rain scatter on the GHz bands.  There are always plenty of aircraft over Europe, so look for aircraft reflection contacts on 1.3 and 2.3GHz up to 800km to work some new squares and make the bands more interesting.

With no major meteor showers peaking in the upcoming week, we’ll be relying on sporadic E on the low VHF bands. The season is still giving some occasional good days from the UK, although the present period of rather weak jet streams, which are often a good indicator of where sporadic E may develop, means that the sporadic E events may be limited both in scope and the highest band available.

We are past this Moon cycle’s apogee again but with minimum declination occurring only yesterday it is still negative for the upcoming week. Losses will continue to be high, so EME opportunities will be short.

Category: GB2RS Propagation News