Propagation News – 28 May 2023

The Sun currently has an equal number of spots in both its Northern and Southern hemispheres.

The Solar Flux Index was consistently in the 150 to 160s range last week, with a total of eight M-class flares. We had unsettled geomagnetic conditions on the 21 and 22 May when the Kp index hit six, but things then settled down again to a more manageable two to three.

There are times when the F-layer critical frequency is lower than the E-layer critical frequency due to Sporadic-E. This means that HF signals can’t reach the F2-layer, basically blocking off DX, but leaving Sporadic-E short skip available. So, make the most of these short-skip contacts to the continent and multi-hop Sporadic-E skips to further afield. Conditions in the F2-layer will improve in the autumn, so don’t worry!

There is still HF DX to be had, but you may have to hunt for it. Recently, Laurie, G3UML worked BD4VGZ in China on the 15m band using CW and Stuart, M1SMH worked YG2ALQ in Indonesia as well as A71UN in Qatar, on the 10m band using FT8. Meanwhile, Andy, M0NKR worked VK on the 15m band using SSB long path. Namibia, Malawi and Equatorial Guinea have all been workable from the UK using FT8 on the 10m band during late morning.

Next week NOAA predicts that the Solar Flux Index will remain in the same range. That is, in the 150 to 160s. Unsettled geomagnetic conditions are forecast from the 2 to the 4 June, when the Kp index might reach four. Otherwise, it suggests that conditions will be mainly settled with the Kp index around two to three.

So, make the most of the elusive HF F2-layer openings and the various opportunities available during this peak time for Sporadic-E propagation.

VHF and up

The broad scale pattern is still dominated by a large area of high pressure over the country with its centre mostly to the northwest of the British Isles.

The whole period through to the end of the coming week should offer some good tropo prospects, so why not try using CW or SSB to add some extra squares to your log? Under lift conditions, even a halo antenna can be surprisingly effective.

The weather variety will remain until the end of next week when low pressure over France tries to push some thundery showers northwards into southern Britain after midweek, and perhaps then northwards as far as western Scotland. This brings a chance of rain scatter on the GHz bands.

There is, as usual, always a chance of aurora and meteor scatter to bring additional options, but the main mode of interest this week will be Sporadic-E as we head into the peak of the season.

With tropo also in play, it’s worth a quick note for those not used to working Sporadic-E; Tropo tends to be long-lasting and usually better on the higher bands. That is to say, the 70cm band is often better than the 2m band whereas Sporadic-E is usually brief and better at lower frequency bands. So, the 10m band is better than the 6m band.

This time of the year it can reach up to 2m on rare occasions. If you do nothing else, simply check the bands and clusters at the end of the afternoon to maximise your Sporadic-E chances.

Moon declination is positive but falling this weekend, going negative on Tuesday. We are past apogee so path losses will fall as the week goes on. We’ll see shortening Moon windows with falling path losses. 144MHz sky noise is low all week.

Category: GB2RS Propagation News