Propagation News – 11 March 2018

| March 9, 2018

Quieter geomagnetic conditions helped improve HF propagation this week. At times the K-index was actually zero, thanks to a respite from the continual coronal holes on the Sun that have caused disruption. The solar flux index continued to hover around the high 60s due to a lack of visible sunspots.

Despite this there was plenty of DX to be had. Chris, G0DWV with a well-equipped station, reports working nearly every state in the US during last weekend’s ARRL International DX Contest. Others were busy chasing 3C3W in Equatorial Guinea, XR0YD on Easter Island, 3D2EU on Rotuma Island and S01WS in Western Sahara among others. This just shows that quiet geomagnetic conditions can benefit DX hunting, even if there are zero sunspots.

Next week NOAA predicts the solar flux index will be between 68 and 72, and we may have quiet geomagnetic conditions until around the 15th when the effects of a large coronal hole may see the K-index rise to four or five. The unsettled conditions are predicted to last until the 19th.

The near real-time critical frequency and computed MUF charts at show that 20 and 17 metres remain the best daytime DX bands, with occasional openings on 15m. Eighty and 60 metres remain the best bands for inter-G working.

VHF and up

Next week will bring little in the way of tropo, with low pressure and windy conditions at times throughout the week. If we were another month ahead in our journey into spring, the other item on the agenda would be sporadic E. Sadly we’re not, so this month it’s very much a long shot.

Since jet streams are involved in Es, we are in fair shape in this unsettled weather type, but the jet stream is still well south of us. This favours paths across the Mediterranean, rather than any within reach of the UK.

This is all a bit speculative really, and in this sense if anything does occur, it’s more likely to be of benefit to those low-signal digital modes like FT8, rather than more traditional CW or SSB.

Of course we’re never completely without hope of getting gigahertz bands rain scatter in such unsettled weather. Now land temperatures are picking up we are testing those April showers, which are more likely within reach overland.

This Sunday the Moon is at apogee and minimum declination so EME path losses are at their highest and Moon windows shortest. We are seven days away from positive declination so this week is probably best spent checking your antennas after the cold weather.

Category: GB2RS Propagation News