A little while back there was some discussion about the range of Wi-Fy.
And specificly if a 20 mile range was achievable. Here is something I
ran across on the internet.

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On Saturday, December 6, 2003 a group of students from Weber State
University demonstrated 802.11b networking over a distance of 82 miles
using off-the-shelf hardware and software. 
It was a line of sight shot across the Great Salt Lake in UTAH.
They used DSS Modified for the Wi-Fi band Dish antennas and a 1.5 Watt
amplifier.
The record for Unamplified Wi-Fi is 70.5Km(32.9 Miles) set across water
between two of the Canary Islands.
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 Now to be fair the first one was done under an expermential permit and
would be Illegal for day to day use as the FCC specificlt sets limits on
Effectiave Radiated Power. But while the application of the second one
could be limited except in the Flat lands of the midwest Point ot Point
ranges far beyond what it typical are posable.
The key is that it is Truly Line of Sight. IF standing beside yuor
antenna you cannot Physicaly see the recieving antenna the chance of
sucess is low.          
Both those attempts used an old Primestar DBS dish and a "Nalley Big
Chunk Beef Stew Can" as a "Waveguide Antenna" in the focal spot of the
DBS dish.

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