I helped install a wireless bridge between a house and nearby shop. The guy who we'll call Adrian could get broadband at home but not at work so we needed to network the buildings.
Version 0.1 of the bridge was the wireless router (Buffalo WHR-HP-G54) and a "wireless ethernet converter" aka bridge (Buffalo WLI-TX4-G54HP). The first device is a normal router that also works as an access point. The second detects and connects wirelessly to the first and provides 4 ethernet plugs for devices that will "see" it as a plain switch so no wireless software needed at all. The Netgear wg602 can also do this.
These devices were placed in the two adjacent buidings near windows and detected one another immediately. Unfortunately the link was unreliable. If you want a wireless bridge you need it to work all the time. This means aerials with line of sight.
Shopping for wireless antennas is baffling because of connectors. It turns out that most wireless routers require a cable with an rp-sma MALE connector (female threaded!) and most aerials need cable with N-male (female threaded!) connector. A list of models and their connectors here.
I chose directional panel antennas (Micro Beam MB24PL10NF) which are small and subtle. Adrian attached one to guttering using rivets and a bracket
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and another to a metal facia just with rivets.
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