"Glenn Ashmore" wrote in message
...
I think it would be wise to learn something about 2.4ghz wave propagation
and the Fresnel effect before you make that statement. If you just want a
couple of hundred yards range deck mounting is fine but for 2 miles plus
you need to be UP.

The maximum radius of the first Fresnel zone for 2 miles is 33 feet. So if
the tower is at 66 feet, the path is clear. Even if there was a large
reflection in the first zone, the maximum phase deviation would be 90
degrees, a phase quadrature signal, which would make the link even more
immune to fading and could increase the recieved signal strength as Wilbur
has reported.



By far the best solution is a waterproof wifi bridge at the masthead
connected by Ethernet with POE to a hub. Long range because there is
minimal coax loss and a wide Fresnel zone.

The Fresnel zone does not become any wider with that mounting installation,
it is just that there are less object to protrude into it.

The concept of a Fresnel zone is just a crude rule of thumb calculation to
prevent multipath. It doesn't take into account antenna beamwidth or any of
the physical properties of the in-path scatterers. It's great for
determining cell phone tower sites but is completely meaningless for
actually estimating what signals arrive at the antenna. You can place a
vertical aligned metal grid directly in the path of a horizontally polarized
signal and see virtually no effect yet the Fresnel rule of thumb would say
otherwise. The Fresnel rule of thumb sees no difference between vegetation
and buildings, it provides no insight into wave propagation at all.





--
Glenn Ashmore