Wireless network questions

[Bill Nash]

Ummmm, we used the plans linked from the various slashdot pieces about
them. The most effort required was building the waveguide, and the hardest
part there was just finding aluminum tubing. We wound up scavenging from a
roof mounted TV antenna. We aren't sure who it belonged to, though. It's
funny how things work out when you're just wandering around with clippers
in your hand. The rest of the wave guide is just a five inch piece of all
thread, with some washers. Home Depot carries them. Make sure the washers
you select FIT on the allthread before you leave the store. Don't ask if
we made a second trip. Don't ask what my drill bits are made of, either.
Locking nuts on either end of the allthread keep it together.

Keep in mind, this project was pulled off by hooligans for whom power
tools are verboten. Had wife/girlfriend figures known what we had been up
to, this would never have been written. Just for less pain, I recommend
picking up two cans for each antenna you're planning to build. One, in
case you screw up. Two, the extra lid, minus about 2mm of it's outer edge
(accomplished with simple scissors) is perfect for the inside end of the
waveguide. And if you like Pringles, you get more.

We cut some schedule 40 PVC for our mounting apparatus, which worked out
pretty well. Using a length about six inches longer than the pringles can,
we cut the PVC in half, except for that last six inches. We set the can
into the slot, hot glued it in, and then drilled the still-whole part
through so we could side mount a u-bolt onto it. (Hint, drill those holes
on the same axis on which you cut the pipe in half.) If you're not
mounting it, this still leaves you with a good handle with which to test
for RF burns on your friends (joke, I swear.)

The important part to remember about the hot glue, especially in AZ, is to
make sure that when you mount it, the PVC is on the underside. Running a
ring of hot glue around the can like a rubber band helped, too. Our first
go around, we suffered dramatic signal loss when one of the cans took a
dive off the mount. Oops. We picked up some female N connectors at Fry's,
for installing the load into the can (By the by, proper measurements using
a can of plain pringles has your load hole going in right about where it
says Sodium on the list of things that will kill you if you eat the
chips.) Ideally, the copper load should be just behind the end of the
waveguide.

When it came down to the WEP11's, oh man, now there was an adventure. They
use the RTNC connectors for the antennae they sport, which you cannot find
locally. Well, stock ones do. Both of mine now have one RTNC, and one BNC
connector. The firmware allows you to turn one antenna off, which we did,
since we didn't need indoor access on these APs. No point in confusing the
little PC card any more than we already were. Figuring out how to get
those slick little blue cases open was fun. I dremel'd one like a jigsaw
because I was too geeky to just yank on the front. That and I love
dremelling things.

We picked up the RG6 after we discovered Rg58 just wasn't up to the task.
With our 50 foot RG58 runs, we were losing so much of the signal that
we got about 20 feet of signal out through the can. I probably could have
done the math on this had I known better, but hey, getting there is half
the fun. I could have done without the repeat attic crawls, though. We
crimped BNC on one end, and used twist on/soldered load N connectors for
the Can connection. Fry's poor selection dictated our choices, there. That
and every other electronics place in town, from Greybar on through the
yellow pages doesn't carry RTNC. You have to order them, usually from some
Ampenol distributer. We were in a hurry, so this wasn't an option.

The drawback to RG6 is that it's about a buck a foot, and about a pound a
foot, now that I think on it. It's about half an inch thick or so, too,
and gets VERY pliable under the sun. Caveat emptor.

We grabbed a couple of tripods and six foot masts from Fry's, as well.
When all was said and done, we had only a couple milliseconds of latency
at full speeds, and since one of the cans was Sour Cream and Onions, some
really wierd gas. The cans took the summer heat pretty well for a couple
of weeks. The cool thing about pringles cans is that new ones are cheap,
and once you build the waveguides and assemble other parts, you can keep
them in a drawer for when you need fast temporary link-ups.

- billn

On Mon, 10 Mar 2003, technomage wrote:

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> do you happen to have plans available for those "cantennas" (aka pringles
> antenna)?
>
> Mage
>
> On Sunday 09 March 2003 03:53 pm, Bill Nash wrote:
> > On Sun, 9 Mar 2003, Alan Dayley wrote:
> > > On Sunday 09 March 2003 11:00, David Mandala wrote:
> > > > Pigtail MUST be short at least as short as possible <20 feet preferred.
> > > > Power falls off fast in cable runs. IBM makes a card with almost 2x the
> > > > power of the Lucent cards, I'd use them. Can you just go over the roof,
> > > > the extra distance (length of a house) in the air is almost irrelevant.
> > >
> > > Yes, the distance over the house would be trivial.  I am pretty sure we
> > > can arrange things at both ends to accomodate short pigtails.  Thanks.
> >
> > 	An other (slightly costly) alternative is heavy coax for your
> > external 'CANtenna' run. If you're not talking about long distance, the
> > signal loss will likely be negligible. When I say heavy, I mean *heavy*,
> > like RG6. We ran a pair of linksys WAP11s, with actual Pringles cans, over
> > about 100 yards, at full speed, using two ~40' runs of RG6 coax. If WAP
> > placement is a problem with relation to your antenna, this might help a
> > little.
> >
> > - billn
> >
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> - --
> I will not be pushed, filed, stamped, indexed, briefed, debriefed, or
> numbered!
> My life is my own - No. 6
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