Hack 86. Pirouette Can Waveguide
Build a simpler, higher-gain antenna-in-a-can.
Since the Pringles can story [Hack #85] was published, many have people said, "You know, that's not a bad design, but some friends and I found a better way to do it." One such person was Gregory Rehm. He took the Pringles can design, and another coffee can design, and pitted them against his own designs (including a 40 oz stew can) in a Wireless Cantenna Shoot-Out Battle Royale. His experimentation and excellent analysis is documented on his web site at http://www.turnpoint.net/wireless/has.html. It is entertaining to read (and in case you're too filled with suspense to wait until you can check his site, his stew can won by a mile).
As it turns out, it is much simpler to make a tin can waveguide antenna than to bother with cutting pipe and spacing washers apart on all-thread. He has an excellent how-to posted online at http://www.turnpoint.net/wireless/cantennahowto.html, complete with photos, diagrams, and formulae.
Another common can that approaches the ideal diameter for 2.4 GHz is the Pepperidge Farm Pirouette can (see Figure 6-6). It makes a much simpler, sturdier, and more efficient antenna than a Pringles antenna, and the best part is, you get to eat the cookies!
Figure 6-6. The Pirouette cantenna
Essentially, you are looking for a can that is about 3 1/2" in diameter. Make an N connector with a 1.2" intentional radiator (just as used in the Pringles Can Waveguide [Hack #85]), and attach it to the Pirouette can about 1.9" from its back surface.
Presto, you have an instant waveguide without cutting a single piece of pipe!
6.5.1. See Also
- The ARRL Antenna Book, by R. Dean Straw, Contributor
- The ARRL Microwave Experimenter's Guide, by Dana G. Reed, Editor