Building Wireless Community Networks, Second Edition

Home-Brew Antennas

Since the first edition of this book was published, many new home-brew antenna designs that work at 2.4GHz have been published online (and more are being thought up every day). Here are just two ingenious examples.

The Pringles Can

At the Portland Summit in June 2001, Andrew Clapp (http://www.netscum.com/~clapp/) presented a novel yagi antenna design. It used a bolt, metal tubing, washers, and PVC tubing to make an inexpensive "shotgun” yagi, either 18” or 36” long. While his antenna shows between 12 and 15dBi gain (which is impressive for such a simple design), it’s also quite large. When we returned from Portland, some members of our local group and I realized that, if we were careful, we could fit a full wavelength inside of a Pringles can as shown in Figure 7-1. This would show a reduced total gain, but it would also make the entire antenna much more compact.

Figure 7-1. The complete antenna (it’s just a can!)

Parts list:

Part	Approximate cost
All-thread, 5 5/8” long, 1/8” OD	$1.00
Two nylon lock nuts	$0.10
Five 1” washers, 1/8” ID	$0.10
6” aluminum tubing, 1/4” ID	$0.75
A connector to match your radio pigtail(we used a female N connector)	$3.00
1 1/2” piece of 12 gauge solid copper wire(we used ground wire from house electrical wiring)	negligible
A tall Pringles can(any flavor, Ridges are optional)	$1.50
Scrap plastic disc, 3” across(like another ...