In a message dated 97-07-07 08:23:09 EDT, W8JI writes:
<<
If the signals duct, why does the saltwater path help?
>>
Because it is a uniform surface of water, helping to maintain uniform layer
of duct. In a uniform or smoothly curved duct, we get smooth refraction of
signal which gets "trapped" in the duct and is enhanced. When you get over
land, irregular terain with updrafts of warmer air "break up" the layer
(different dielectric constant), make them "bumpy" and inneficient to
propagate the signals in the duct.
The other possibility is what Tesla speculated, that the ocean (earth) is a
one plate of capacitor (maybe electrode in a space "vacuum" tube), ionosphere
is the other one, and signal gets propagated, maybe even amplified between
them.
I'd love to fly up in the shuttle or other suitable vehicle with my radios
and play in the 160m contest!
That's my 2 cents (Canadian) worth.
73 Yuri VE3BMV, K3BU
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