N5OOM's HSMM Projects John Beadles is the president of a club in Texas that has done lots of really good work on the wifi stuff. Some of it is really quite technical, but his power points and explanations are very lucid and easy to understand. Have a look at them and I'd be happy to fill in any gaps or questions that you might have.
John's rootenna project. Something like what he has shown can be done by ogWiFi Antenna WG in the $200 range; This is sfor the ENTIRE system. If you buy a commercial set up like this, you would pay at least an order of magnitude more (that is ~$2000, folks) for a system that would be nearly as good as ours, but not quite. I'd like to come up with a standard for hardware like this that can be easily replicated, is easy to troubleshoot and install and will stand our severe weather without generating many site visits.
We are convinced that the antenna of choice for most WLANs of our nature is the age old waveguide. Apparently ... the slot array was invented in 1943 at McGill University in Montreal. Unique features of these antennas are horizontal polarization and omnidirectional gain around the azimuth. They are also simple, rugged, and fairly easy to build. While they have been described in several articles in the ham radio literature, all the articles seem to have the same dimensions, suggesting a common genesis.... (Paul Wade W1GHZ)
Commercial waveguides begin around $50 CDN and go upwards in price. There are many factors that contribute to the price, however we are considering these three characteristics and hoping to keep the overall price low. These are: (1)Gain; (2)Durability ; (3) Size.
Doug and I have an idea that we can design a reasonable 19DBi waveguide, with 170 degree radiation pattern, from 16 gauge galvanized steel "bottom track" (standard construction grade metal stud framing material) for about $15 per antenna. Once we get some time for building a few prototypes, we will post our findings.