Wednesday, May 23, 2007 at 22:20
Doug, FYI there are various kinds of ducting such as tropospheric and ionaspheric. They affect different bands of frequencies.
We used tropo as secure comms over 800k in asia, by bouncing the signals on ionized meteor trails.
The mechanism is temporary but relatively easy to predict. However it is a specialist field, used largely by radio amateurs for long distance contacts.
Interestingly enough, HF waves can also be reflected back off objects, and this is the basis of our over the horizon radar systems in Australia. So the next time a plane goes over your aerial, listen for a bit of "flutter" .
BTW I heard some South Oz amateurs on the TV around Xmas in 1958. That's what started me interested in getting my license. I also heard Taxis, but I never wanted to drive one :)))
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