Propagation News – 14 January 2024

We couldn’t have asked for better solar conditions last week. We had a low Kp index that never got any higher than 2.67, and a solar flux index that started the week at 167 and then rose to 186 by Wednesday.

So, at first glance, this looks like ideal conditions for HF. However, we are in the middle of winter and therefore the ionosphere is not at its best. The low bands are also being affected by the higher solar flux and, on the whole, the 14MHz band and above are closing as the night draws in.

Daytime critical frequencies remain around 9 to 10MHz, so the 40m band should remain useful for inter-UK work. Nighttime critical frequencies are currently falling to 3.5 to 4.5MHz, which means the 40m band is only open to long skip, if at all.

The critical frequency is the highest that still returns a signal from the ionosphere if sent straight up, and is a good guide as to which bands are open to near vertical incidence skywave or NVIS signals around the UK.

On the brighter side, 14MHz has been showing signs of DX. The VK6RBP beacon has been heard on 14.100MHz in the afternoon via the short path and 28.200MHz in the morning via the long path.

The 12m band has shown international beacons RR90 in Siberia, OH2B in Finland, LU4AA in Argentina and YV5B in Venezuela, on 24.930MHz in the morning. While the 10m band also highlighted YV5B in Venezuela during mid-morning.

Not a massive catch, but better than we were getting two years ago!

For the coming week, NOAA predicts that the solar flux index may fall into the range 150 to 165. Geomagnetic conditions are predicted to remain settled with a maximum Kp index of 2.

As always, this could easily change if we have a coronal mass ejection, so keep an eye on solarham.net for near real-time solar conditions.

VHF and up

The area of high pressure has been working well for some parts of the country, with Tropo conditions lasting into the start of this weekend, but as a cold front moves South on Saturday 13 January, all will change as the high becomes displaced to the Atlantic.

Therefore, there is no significant Tropo for the coming week, but there may be some rain scatter from showers, especially around the coasts.

We seem to have passed the period of unusual winter Sporadic-E propagation without much evidence of activity, so that just leaves meteor scatter. After the Quadrantids last week, we entered a period of low meteor shower activity, leaving just random meteors until the next major shower, the Lyrids in April.

For random meteor scatter, the pre-dawn period works best. The solar conditions can still be instrumental in producing extra propagation treats with chance aurora. Probably the best operating policy is to monitor the geomagnetic Kp-index with high values greater than 6 being a good sign for VHF.

For EME operators, this week starts with very low Moon declination, low peak Moon elevation and short Moon windows, but declination is rising and goes positive again on Tuesday. Path losses are still low, and reached minimum at perigee on Saturday 13 January. 144MHz sky noise is low for all of the coming week.

Category: GB2RS Propagation News