sabato 1 luglio 2017

Propagation News – 2 July 2017

This week NASA confirmed that we are heading for solar minimum, with the low point expected in 2019-2020. It also said that this may bring more long-lived coronal hole activity. This should come as no surprise to radio amateurs as we have been reporting near-minimum solar flux index levels and the ongoing effects of coronal holes for many months. Last week, the solar flux index hovered around the low 70s, but geomagnetic conditions were relatively settled with a K-index in the range zero to two.

Nevertheless, as we are in the summer HF doldrums, F2 layer maximum usable frequencies for amateurs often struggled to get above 18MHz during daytime.

A quick listen on the 14.100MHz International Beacon Network frequency on Thursday afternoon showed RR90 coming in from Russia and OH2B from Finland, and that was about it. OH2B was also audible on 18.110MHz. However, some better-equipped stations reported they had worked the B7CRA IOTA DXpedition in China on 20m, so there is always DX to be had if you know where to look.

Next week, NOAA predicts the solar flux index will remain in the mid-70s and geomagnetic conditions should be settled. A view of the Sun in extreme ultraviolet showed no earth-facing coronal holes, so make the most of the quieter conditions and continuing sporadic E openings.

It might also be an opportunity to head for the hills and try some portable HF DXing, with the added benefit of lower noise levels.

VHF and up:

The coming week starts with low pressure nearby over Scandinavia and another low moving towards north-western Britain. In the south of the country a weak high may give some tropo conditions at the end of the weekend and for part of next week, although there is a chance it will collapse before mid-week. The principal tropo directions are to the south into France and northern Spain.

We had some good rain scatter on 10GHz last week with paths open across southern England and over to northern France, but sadly little UK activity to take advantage of it. The tendency for low pressure in the north, and perhaps later in the south, will mean that more rain scatter should be possible in any summer thundery showers.

The sporadic E season still offers opportunities for the bands from 28 to 144MHz to suddenly spring into action. Prime times to check are late morning and again late afternoon and early evening. A 144MHz opening is likely to be a rare event, but 28, 50, and 70MHz openings are commonplace at this time of the year.

An encouraging number of UK stations turned out for the UK Microwave Group’s 10GHz contest and a few took part in the Dubus moonbounce contest on the band.  There are a growing number of UK stations active on moonbounce above 1GHz, where there is good activity and plenty of DX to work.

The upcoming week has negative Moon declination and high losses due to its apogee, or furthest point from Earth, on Thursday, so activity will be lower, making it a good week to further optimise those EME systems using solar noise.