propquest
Introduction
This website was created to explain why conditions on our 80m Norfolk Amateur Radio Club Monday night nets on 3.545MHz in the evening at 2030 local time were so variable. Firstly, a 24 hour plot shows the typical diurnal variation of foF2, as seen in the various propagation texts and most amateurs will be aware of the broad sequence of events during the day. What does become interesting is why one day sounds very different to another on the bands and the graphs make this very obvious.

Of course, for a local net you will be using a near vertical incidence skywave (NVIS) refraction from the F2 layer, so the foF2 is a good guide for conditions. This display system has been tested by our club members over a few weeks and several useful operating features have become apparent already.
  1. A marked minimum just before dawn, but of course at the height of the F2, this will come much earlier than at the surface, so the curve kicks upwards long before sunrise at ground level.
  2. Steep rise to the typical daytime value, but always lots of variation during the daytime period. Band conditions will probably suffer from some D layer absorption too (not shown), which will affect the LF bands such as 160m, 80m 60m and 40m, so all is not as good as the graphs might suggest on the LF bands.
  3. Rapid fall off of the foF2 as the solar insolation decays towards sunset. Often a brief window when the D layer absorption has gone and still some ionisation left for foF2 short skip paths within the British Isles late afternoon.
  4. There is usually an evening dip, but the times can vary from early to mid evening, followed by a late evening rise in foF2 for the early hours before fading into the pre-dawn minimum.
  5. The F2 MUF distance seems to be a very reliable guide. The end of the SSB AFS contest faded quickly leaving just a few stations audible in Norfolk from SW England and Cumbria plus GMs, all confirmed by the 500km F2 MUF being just above 3.5MHz, whereas the foF2 was way below 80m.
  6. Once the foF2 has fallen to below your operating frequency, say 3.5MHz, then the bands appear to go ‘long skip’ and this is usually confirmed by the F2 MUF for 3.5MHz only available for distances of 1000km or more with plenty of eastern European stations coming through and not a G to be heard.
  7. If you are just interested in the close-in UK conditions for your local nets, then switch off the 3000km F2 MUF to see the foF2 or short skip 100km detail more clearly.
  8. foEs has proved very useful in a recent net when the foF2 was around 2.1MHz, yet the 3.5MHz signals were very strong over all local stations, plus out to at least 100km. It turns out that the foEs was 4-5MHz at the time and the most likely propagation was via the E layer.
  9. The 3000km F2 MUF can give a heads-up on which of the HF bands may be worth checking, since these will not be adversely affected by D layer absorption.
Several new sections have been added as the site has developed. The Es Blog is used to follow upper air jet stream charts and describe daily Es chances during the main summer season. The EPI section is a new attempt to isolate the main ingredients behind the formation of Es and combine them into a single probability index.
User Guide
Introduction
foF2
Es Blog
EPI
Credits and data
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