[lug] cheap 802.11b for linux...

[J. Wayde Allen]

On Thu, 21 Mar 2002, Rob Nagler wrote:

> No choice here.  The TNC is on the Linksys.  The BNC is on the
> antenna ( http://www.superpass.com/SPDG16O.html )

Yes I understand.  Also, it is probably worth noting that my experience
is from the point of view of precision RF measurements where repeatability
of the connection is very important.  I believe that the TNC connector is
rated for use up to 4 GHz, but it is kind of uncommon to see it used at
GHz frequencies.  Especially in the metrology world.

> Nate said something about wire.  I'm using RG-58, which I assume is
> bad even for a less than 6ft?

Bad is kind of subjective in this game.  RG-58 is mostly used for
HF/VHF/UHF communications.  You will see a lot of RG-58 in television
wiring for this reason.  It really isn't designed for use at microwave
frequencies.  Some URL's to check out are:

http://www.radiobooks.com/products/techinfo/coaxloss.htm
http://rf.rfglobalnet.com/library/ApplicationNotes/files/2/times.app.txt.htm
http://www.amsat.org/amsat/articles/houston-net/coax.html
http://rf.rfglobalnet.com/library/ApplicationNotes/categories/2.htm

> I've built some power-over-ethernet modules.  My plan is to mount the
> Linksys on the inside of the roof just below the antenna and so the
> only coax would be the length from the antenna through the roof.

That ought to work.

> I thought about buying a casing, but frankly I can't see something
> that's going to protect the Linksys in Boulder's climate.  I want to
> be able to replicate the set up at the clients.  (I'm using the
> Linksys in bridging mode.)

I've been looking at some of the weatherproof electrical boxes sold at
Home Depot.  These cost about $20 and look like they'd work pretty well.

> I've been to Saunders, and their grounding cable seems very
> expensive.

Probably, they aren't necessarily the least expensive source of things.  
Try someplace like a hardware store that sells electrical wiring.

> I would like a roof tripod for my antenna.

Those are available for instant gratification at Radio Shack, McGuckings,
and Home Depot.

> Someone else mentioned weather as important factor.  What I found is
> that obstacles, especially trees, are the key factors.  I need to test
> the placement when the cottonwoods are full.

Yes indeed.  Lots of things absorb energy at 2.4 GHz.

> Does anybody recommend putting two antennas?  The Linksys allows you
> to control which antenna you use.  My feeling is that all get more
> loss by placing two antennas far apart than going with one antenna and
> telling the Linksys to use only one.

Not sure about the double antenna idea.  I think the Linksys unit
dynamically chooses the antenna that gets the most signal, which
"might" have some merit.  However, I'm pretty certain that this isn't a
smart antenna array so am unsure that it will gain you much.  Basically,
your reasoning sounds good to me.

> 
> There is this guy who is getting a lot of press for is wireless
> network in Aspen.  That's the first article.  The second article is
> just interesting, because it is connected to Sun's lab in Aspen.
> There are a lot of pictures.
> 
> http://lists.nycwireless.net/pipermail/nycwireless/2001q4/001339.html
> http://www.key3media.com/interop/atlanta2000/presentations/General_Conference/Wireless/C8_Branscomb.pdf

Interesting.

- Wayde
  (wallen at lug.boulder.co.us)