[Cu-wireless] Antenna design shootout

[David Young]

On Fri, Apr 12, 2002 at 03:30:03PM -0500, Ralph Johnson wrote:
> See http://www.turnpoint.net/wireless/has.html
> 

I've seen this before. They reach a lot different conclusions about the
Pringles can antenna than we do. This isn't enough reason to reject
their conclusions (maybe we just can't read the Lucent signal meter)
but we get better results than they do, over and over.

They say that the aluminized insides of the Pringles can antenna are
not conductive, but this just isn't so, at least not in the Illinoisan
varieties we've used. (Some people seem to think that there are "regional
differences" between Pringles. I doubt it.)

It IS so that the metal bottom of the can is NOT electrically attached
to the aluminized insides. I don't know if that matters, though. Consider
that the can's bottom is shaped like this if you look at it on edge:

   ________________
|_|                |_|

 ^                  ^
 |                  |

The aluminized cardboard tube fits in where I drew the arrows. I think
this is essentially the same way that rotatable joints are made in even
the costliest waveguide gear. That is, there is no electrical contact,
but a tongue & groove configuration.

Those great big cans (for beef stew, for Yuban(tm) coffee, etc.) are
definitely worth a try.

Incidentally, someone e-mailed me an annotated copy of the Yuban antenna
Web site with some great info. I am happy to share it. Just ask.

Can anyone tell our merry band of wireless volunteers whether we will
take a "gain penalty" by mounting a Yuban antenna in direct electrical
contact with our all-metal antenna mounting equipment?  I.e., will the
whole mount radiate in some god-awful pattern? The cardboard in our
Pringles can antennas keeps them from contacting our mounts.

Dave

-- 
David Young             OJC Art & Engineering
dyoung at onthejob.net     Urbana, IL * (217) 278-3933