"Robert11" wrote in message
. ..
Hello,

For the scanner frequencies in general from approx.140 MHz to 1 GHz, is
propagation truly
line-of-site "totally", or is there bending of the signals by some
atmospheric layer possible at various times ?

Any around 156 MHz fm in particular ?

Is there ever any "ducting" ?

Thanks,
B.



Typically you can expect 20% further than calculated line of sight range on
VHF frequencies. Signals grazing over distant hills can also enhance range
somewhat. Higher frequencies will tend to conform more tightly to line of
sight.

Ionospheric disturbances and ducting (usually in the summer months) can lead
to VHF signals being received at ranges of up to a 1,000 miles, sometimes
more.

Mike G0ULI