-----Original Message-----
>> If you want the local F2 Critical frequency (the one where signals go
>> almost straight up and down, try looking at this map.
>> http://www.spacew.com/www/fof2.html
>Excellent map for this.
>For paths that are more typical of "DX" (3000 km paths), there is also
>this map:
>http://www.spacew.com/www/realtime.html
That's the 'other' map on that site. :-)
The problem always seems to me to be that it is 'DX' that many people
concentrate on, when a lot of the paths most people actually use are high
angle.
Think of it, antennas fairly low to the ground (in terms of wavelength) and
that, for a lot of the time, you are asleep when 'DX' stations are awake,
and vice versa.
Yes, I know people do stay up late, and get up early, but it is 21:45UTC
here and I'm typing this and not tuning round the bands. ;-)
OK, the 'DXers' put up low angle radiating antennas, and listen all day and
all night, but the average radio enthusiast today, I would argue, does not
put in the same time or effort.
So, most Amateur contacts on HF are likely to be high angle and local to
semi-local in nature.
Strangely, the new allocation on 5MHz has meant that, because there's no
'DX' to be had (yes, there is one frequency that the USA and the UK share,
but that shows the need for low angle radiation and propagation to be right)
most contacts require that antennas be high angle 'cloud warmers' to contact
other people on the same band.
Once you start to understand this, the same effects on 80M, 40M and 30M
start to make more sense. Antennas low, in terms of wavelength, and times
of day when the F2 critical frequency for NVIS helps. At the edges of the
bands useful for NVIS (like 80M/160M and, possibly, 30M) propagation comes
and goes and, especially on 30M, antennas are on the edge of providing low
angle radiation, and brief NVIS openings only when conditions are right.
The problem may be that training schemes for new Radio Amateurs major upon
'DX' propagation, leaving people wondering why they hear lots of stations,
when the bands are supposed to be 'dead', and the reality is that you can
work a lot of stations over short to medium length paths using NVIS and less
than optimal, for low angle DX, antenna techniques.
Maybe this is an historical effect? Possibly, when the number of Amateurs
was small and 'DX' was all, the need was to try to predict the best time to
hear someone a long way away. Now-a-days, there's a lot more Amateurs
about, and a lot of them are closer to you, but the desire for better 'DX'
still nags at the corners of our minds? Yet, we can talk to more people if
we are prepared to use NVIS than if we go all out for 'DX'.
In a world where the professionals tell us there's nothing they need
Amateurs to find out any more, maybe we need to learn how best to talk to
people who are not very far away? Or even, if we do talk to them anyway,
what modes of propagation we are using.
I count 'talking' to mean all the modes of propagation as well, as I use CW
and prefer to make contact with someone (anyone!) than no-one at all.
Dave (G0DJA)
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