Propagation News – 10 April 2016

It is beginning to look like we’re getting an early taste of the upcoming solar minimum. The sun currently only has one small sunspot group and, at the time of writing, there were no new spots coming up behind it. The solar flux index hovered in the low to mid-eighties this week, giving a noon-time critical frequency of 5.9MHz on Tuesday and 5.2MHz on Wednesday, as measured at Chilton, near Harwell. These figures suggest that the maximum usable frequency over a 3,000km path struggled to get up to 15m, although FT4JA on Juan de Nova has been audible on 12 metres at times. Forty metres was only open to Europe and beyond, after losing its valuable inter-G capabilities.

The earth was hit by yet more plasma from the solar wind in the early hours of Friday, sending the K index up to five.

Next week, NOAA predicts the solar flux index will decline further to around 80. Unsettled geomagnetic conditions are predicted for the 11th to the 14th, thanks to recurring coronal holes on the solar surface and high speed solar wind streams. We suggest you get your HF DXing in on Sunday, before the onslaught from the solar wind.

VHF and up propagation

It will be another unsettled week, with low pressure being the main driving force behind the weather, and we are therefore very unlikely to see any enhanced conditions on VHF or UHF due to tropo. There is, however, still a very good chance of further heavy showers, some thundery, and these big clouds can produce good rain scatter paths on the gigahertz bands.

We mentioned last week that April is the time to start looking on 10m for sporadic-E openings. There were indeed some fleeting European 10m sporadic-E paths logged on the various cluster sites last week. Admittedly, some of these have been beacons and skimmers, but it is worth putting in a human presence on 10m just in case any early season paths are accessible from Britain.

As the moon moves away from perigee, degradation on the EME path will increase throughout the week. The increase will be approximately 1.9dB by next weekend. The early part of this week will be favoured by small EME stations.

The 2016 Lyrids meteor shower peaks on 21 and 22 April. A noticeable increase in meteor rates can be expected from about 16 April.

Category: GB2RS Propagation News