Am 17.10.2017 22:55, schrieb Markus Vester:
As
a crude first Approximation to the model, we might look only at
groundwave and single-hop skywave. For 230 km range, the geometrical
path difference would be 63.3 km (1.37 lambda) for 90 km reflection
height (night), and 40.3 km (0.87 lambda) for 70 km (day).
Ah, so we would expect an optimum performance on 7.44 kHz during
daytime and 4.74 kHz during the nights between DK7FC and DL0AO. The
phase shift would be just 360 deg or 1 lambda then...
For 5170 Hz it is 1.09 lambda during the nights and 1.44 lambda
during the days. That's even closer to 1 lambda or 1.5 lambda, so here
we would expect an even stronger experessed day/night difference, if
this propagation model is reasonable over that distance.
We will check that!
On 2970 Hz: 0.62 lambda at night and 0.4 lambda during daytime, so both
is not really ideal.
970 Hz: 0.21 lambda at night and 0.13 lambda during daytime. That's
fine! So we should prefer 970 Hz, hahaaa!!
73, Stefan
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