That is going to be extremely tough to get signal to. Standard wireless routers transmit a max of 600 feet (200 yards) with no obstructions. I would recommend a wireless bridge between the buildings. It would be best if you could mount the radios outside up high so you have line of site between them. If you cannot get line of site I would still mount them outside each structure and run an ethernet cable back into the structure to attach to your router or AP. For non line of site I would recommend either a Ubiquiti Nanostation Loco M900 or a Ubiquiti Nanostation M2 (one at each building). The M900 can penetrate trees and obstacles better than the M2 but it has less throuput. The max throuput you can really get on the M900 is about...