• View
• Edit
• History
• Print

AntennaWG

David Scobie? and Doug Yuill? have started up an ogWiFi Antenna Working Group.

• They are seriously thinking of building some Waveguide Antennas, that would need to be covered in fiberglass Radome to protect them from the weather. Coincidently Doug is starting to build battery boxes using fiberglass sheets held together with C-clamps and then glued with epoxy fillets. This same technique can also be used for enclosing this antenna design into a radome which should provide 25 years of service before failing. He thinks that should at least get him to his retirement age! Commercial antennas of this caliber cost thousands of dollars *each* but work very very well in WiFi applications. They'll also have to be "canted" but Dave and or I will draw a picture of what the mounting is going to look like. We think we can build these very cheaply.
• Gear Repurposing Doug had some antenna equipment installed at a friend's house that just happens to be a few houses over from where we are currently discussing setting up one of Doug and David's creations. In the interim, we will be repurposing that old equipment and putting it to use soon.
• David has some fresnel zone mapping software he will use to determine the reach of the installation we are planning. This link to the page
• The following are recommended reading resources:

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.

For your edification, there are some great chapters to read on microwave antennas here -- W1GHZ Microwave Antenna Book Online

• Pay special attention to Chapter 7