My research has shown that a Yagi type antenna will satisfy my distance requirements but I am not sure about the signal going though a building. Also, would I need two Yagi antennas, one on each end (my house and his)? What sort of equipment would I need to connect the antenna to my router and what would he need on his end?
If you do not have these particular host devices, then a cheaper alternative might be a 'Yagi' antenna, which is also known as a 'Pringles' antenna since these can easily be made using a few spare parts and a Pringles potato chip can (or other tube-like device). We don't recommend attaching makeshift devices to existing wireless cards or routers, though, since this may violate FCC rules and regulations. However, there are ready-made Yagi devices you can purchase from companies like Cisco, manufactured under the Aironet brand name. These devices can be purchase for $60 or $70, and easily attach to wireless routers (or can be jury-rigged to attach with a few easily-obtained materials from your local electronics store).
Yagi systems are essentially directional antennas, which means you can focus and direct the wireless transmission signal to a receiver -- in this case the wireless card in your friend's notebook computer across in another building. Although the reception is better if you have an unobstructed line-of-site view, since the signals are concentrated they can theoretically penetrate a building or brick wall. The distance improvements experienced with a Yagi antenna will vary on how well you can tweak and focus the tube-like device. It's a little like tuning in a broadcast signal with a homemade crystal radio. It takes some time and patience, but eventually you can effectively focus and direct that wireless beam. Essentially, the longer the Yagi tube, the better the distance. In some cases, people experimenting with antennas of these types have achieved distances of well over 1000 feet, and even more than a half mile on a good day. We found a good source of information on Yagi antennas at the following Web site: http://www.netscum.com/~clapp/wireless.html#concerns.
It is important to point out, though, that Yagi-type solutions -- especially the homegrown versions -- are not typically used for enterprise networks. These are mostly personal and hobbyist affairs. Also, since Yagi antennas focus and concentrate that wireless beam, there is some concern regarding RF radiation. We are already in an era of increasing wireless traffic, so it may not be the best practice to use "gun-like" devices that can focus and zap beams to distance receivers.