"Flounder" wrote in message
ink.net...
There's a layer of air on the surface of the water that has a difference
in
temperature in the air above it. The permitivitty (index of refraction) of
the two layers of air are different. The difference is in the thousandth
decimal place. Because of the difference in the permitivitty a radio wave
striking the upper layer at or below the Brewster angle experiences total
internal reflection. The wave becomes trapped between the water and the
second air layer. Part of the wave does travel in the second layer, at the
boundary. That is the evanescent wave. That is also the type of wave that
allows your prism binoculars to work. The wave also travels at two
different
velocities in the two air layers.
So, looking at the transmitting antenna as an isotropic radiator at 150
MHz,
the layer height at 30 meters how many modes propagate on the sea surface?


You call *that* an explanation??

BTW, these "modes" that you refer to, - are they in any way similiar to the
"modes" in fibre optic transmission systems? They sound like they might be.

If they are, I would be very interested is a *plain* English explanation!
I really should know the difference between multi- and single-mode fibre
optics.

BTW this isn't a trick question. I'm genuinely interested.



Regards


Donal
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