I occasionally get asked what is the maximum possible distance of a Wireless LAN (or WiFi if you prefer) link.
Apparently 124.9 miles (thats 201 km!) and without using amplifiers at that.
This is apparently the current world record.
How was it done?
1x 12' dish antenna and 1x 10' dish antenna fed from 300mW PCMCIA WLAN cards and using home brew feeds.
From their website:
"The record was set from Mt. Potosi 22 miles south of Las Vegas, Nevada to Utah Hill just inside Utah on the Utah/Arizona border.
An un-amplified connection at 11 Mbps was attained and kept up for 3 hours. During this time 11,000 successful pings were made. Both ends of the link were using SSH and logged into the other end. VNC was also used successfully WITHOUT frames being dropped. Ping times varied from 0.01 ms to 400 ms, seeming to average around 10 ms. The connection had an astounding signal strength of -37 dBm, bottoming out at around -50 dBm throughout the 3 hours. The noise levels were around -84 dBm."
See details of the effort here