Finished Amos antenna (wifi project)

Fnord, Mon Nov 07 2011, 12:12AM

Just finished this a little while ago.

Big inverted amos antenna for 2430Mhz (wifi range). Originally invented by Dragoslav Dobričić. I've changed a couple minor things from his construction, but they're basically mechanical aspects that probably don't affect the functionality much.
The plans are available in a pdf on weefi wifi:


This is the 7 dipole version; I didn't have any heavy gauge wire offcuts long enough to do 9, but I'm happy with the signal strength based on some very rough testing. I Haven't made a mount for it yet... just shooting around randomly by hand I got a dozen or so signals of decent quality.



Things that have been modified from the original:
The coax balun specified in the original plans was replaced with a homemade copper tubing variant-
The dielectric and wire from a coax cable was pulled through a 52mm length of .25" standard copper tubing that was bent into a circular shape. To bend the tubing around so tightly without collapsing the walls, it was first filled with molten lead and allowed to cool. After the correct shape was formed the lead was melted back out and the inside was polished up with abrasive compounds on a shoestring. The amount of tube deformation was minimal using this method(within +/- 0.01").

Rather than making element supports from hotglue as the plans called for, I spent the great sum of 97 cents on a pack of plastic pens and used the tubes from those. Zip ties were looped through the tubes and around the element, allowing it to be secured a precise 35.5 mm from the reflector.

And finally I added some rigidity to the reflector itself by breaking some angles on the sides.

The pictures should say enough. The reflector is 26 x 2.95 inches (660x72mm).
I know it's hard to tell what's going on in the balun shots due to the camera flash, sorry.