Thinking of establishing a point to point link between two locations approximately 400m apart. I believe they have line of sight, so would a pair of directional wi-fi antennae (think yagi is the type we need?) be able to work across that distance?
Most probably. A while back I built two wokfi antennas and tested them at 1.2km.
Here's the thread:
http://forums.overclockers.co.uk/showthread.php?t=17601109&highlight=wokfi
Nice one. Looks like I might be able to get 10mbit+ up and down in that case. (I'm going to pay for an antenna on the roof of a datacentre...)