"Szczepan Bialek" wrote in message
...
It seems that at long distances should appear the phenomenon of frequency
doubling.
See: http://www.rp-photonics.com/frequency_doubling.html

Is such?
S*
not that has been reported anywhere i have seen. this is likely because
that at the low amplitudes of radio waves relative to the energies needed to
create non-linear effects the medium is close enough to linear that any
doubling effect is too small to see.