Propagation News – 12 April 2015

| April 10, 2015

Last week we said that the sun was virtually clear, but spots have a habit of popping up from nowhere. This is exactly what did happen, pushing the solar flux index to a high of 126. Geomagnetic conditions were relatively settled, helping to improve HF propagation. This high declined as the week went on and was down to 106 at the time of writing. So once again the western edge of the sun is looking blank.

This week NOAA has its solar flux index prediction at around 135 with geomagnetic conditions remaining settled for the first half of the week an A index of only five. Conditions may deteriorate later in the week with the A index increasing to 20 on the 16th. There remains a chance of moderate flares and radio blackouts.

The optimum working frequency on paths from the UK to South Africa will be 28MHz, with a reliability of around 90% from noon to late afternoon. Ten metres may also open to Brazil with a reliability of about 75%, although 24MHz may be better.

Sixty metres, or 5MHz, and forty metres, or 7MHz, remain the bands of choice for HF contacts around the UK, with 80m, or 3.5MHz, taking over after sunset.

Last week’s tropo lift provided some activity on the VHF and UHF bands. These openings are not that frequent, but this time of year can be useful as large areas of sea fog around the coasts provide ideal ‘tropo bridges’ into the Continent.

After a couple of cold fronts over this weekend disrupt the lift, the coming week will see a return of high pressure in the south, but there are signs of this one being shorter duration and less developed, so take advantage when you can.

The countdown to the Sporadic-E season is under way and it is well worth checking 10m for beacon activity and then 6m, typically from mid April. Remember late morning and late afternoon are the two peak times in the day for Es.

Moon declination will increase during the week, which will increase available moon time for EME. Degradation will decrease as the moon waxes and also moves closer to the Earth at perigee.

The Lyrids meteor shower peaks on the 23rd. From Thursday expect the meteor count to slowly start rising.

And that’s all this week from the propagation team.

Category: GB2RS Propagation News