Propagation News – 1 March 2015

| February 27, 2015

We are now into March with the spring equinox just a few weeks away. With equal illumination on both hemispheres, this is traditionally a good time for north-south contacts on HF, such as UK to South Africa and South America. A detailed analysis using VOACAP online shows a few more factors to consider when planning what bands to use.

In February, a path from the UK to the eastern seaboard of the US had a 12 percent maximum chance of success on 10m. But in March you may need to drop down to 12m to make the contact. It is a similar story on paths to the west coast of the US.

In other words, 10m propagation to the United States is now on the wane as we head towards summer. But on paths to South America, 10m should be open with an 80 to 85 percent probability of success, pretty much as it was in February.

If you are using a VOACAP-based prediction program don’t forget to change the smoothed sunspot number to 62, down slightly from last month.

Finally, we are not in the summer HF doldrums just yet so there is still plenty of DX to be worked. And don’t forget the Commonwealth Contest on 14 and 15 March.

 VHF and up propagation

This next week the windy and generally unsettled theme continues, but there are some quite positive signals for a large high to develop over Ireland from midweek and slowly drift eastwards to be over the country by next weekend.

These winter cold highs are not such strong providers of tropo initially, since the air near the surface is also very dry at first. However, as the high edges away to the east and declines slightly, there is a good chance of some moisture getting trapped under the temperature inversion, especially over western Britain as the weekend approaches.

This may give another period of tropo to get March off to a good VHF/UHF start. As March goes on, the chance of early Sporadic-E events increases, as do the very rare north-south propagation on 50MHz from the extreme south west of the UK.

We are still in the January to April lull in meteor showers, so keep looking for random meteor scatter contacts on the lower bands in the early mornings and aircraft scatter on the higher bands.

The Moon’s declination is falling all next week so UK EME operators will get increasingly shorter moon windows and losses will reach a maximum on Thursday and Friday.

Category: GB2RS Propagation News