Propagation News – 28 June 2020

After the recent excitement of a new Solar Cycle 25 sunspot, it seems the Sun has decided to go back to sleep. We have had zero sunspots since 16 June and the STEREO spacecraft Ahead view shows just one small bright area on the Sun, which might result in a spot in due course. Luckily, geomagnetic conditions remained quiet throughout the week, with a maximum Kp index of two.

The bands were a little lacklustre, other than the continued sporadic E openings, which have brought almost daily fun on 28MHz.

There were F-layer openings to be found on 14MHz, but these were mainly enjoyed by well-equipped stations. Ed, WA6QDQ/KH6 in Hawaii was audible at 0652TUTC on Tuesday, the 23rd, at G3UML’s Hendon QTH. As was William, AL7KC in North Pole, Alaska, who had a big pile up on 14.224MHz.

Early morning does seem to be the best time to get on 14MHz, with Jim, E51JD on the South Cook Islands being reported again as well. But as the day goes on D-layer absorption grows and 14MHz doesn’t sound very lively at all. Fifteen metres was open to Brazil and Paraguay on Thursday afternoon, although this was mostly FT8. Otherwise, it was 10 metres and sporadic E contacts that continued to provide excitement, with one or two North American, South American and Caribbean openings occurring.

Next week NOAA predicts more of the same, with a solar flux index hovering around 68-70 and a maximum Kp index of two.

A weak solar wind stream flowing from a narrow coronal hole could reach Earth beginning on 27 June. A minor geomagnetic disturbance at higher latitudes may be expected.

VHF and up

The heatwave of midweek should be over by this Sunday, so any enhanced sea path tropo will have weakened too. Coasts can be productive for ducts across the North Sea or English Channel and Biscay in any quieter settled window during the week.

Overall, tropo is probably not a mode to rely upon this week, since much of the time we will have low pressure either over the UK or very close by. This will bring periods of rain or showers, many of which could have a chance of thunder and hail. This implies large convective clouds and potentially good GHz bands rain scatter.

That leaves sporadic E, and we are still within the main part of the season, so keep up the usual procedure of checking mid-morning and late afternoon or early evening. Sporadic E is a mode ideally suited for weak signals and digital modes can give good clues as to which directions may open later for CW and SSB as the opening develops. Make use of the good map-based clusters to see if you are close enough to where the paths cross. Ideally the hot spot should be between about 600km and 1,400km away from your station.

Moon declination goes negative today but as perigee is on Monday, path losses will be at their lowest of the lunar month. 144MHz sky temperatures are low today but increasing to a peak of 2700K around midnight next Saturday. Compare this to the usual 300K cold sky temperature at 144MHz, do the maths and, you’ll see that your low noise preamps are not going to help you at this sky temperature!

The June Bootids meteor shower peaked yesterday but continue looking for the best meteor scatter conditions around local dawn.

Category: GB2RS Propagation News