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Old January 12th 06, 06:29 AM posted to rec.radio.amateur.homebrew
Dr. Anton T. Squeegee
 
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Default glass-mount omnidirectional antenna?

In article . com,
says...

snippety

I have searched and searched and so far have not found the same thing
for 2.4 ghz wifi. Does anyone know where I can find one? If not,


If you're serious about decent peformance, stay away from glass
mount antennas for anything other than receive-only. They're worse than
useless for transmitting.

Trust me, I know this. My employer (WA State Patrol) tried some
glass mounts at one time for their undercover cars. Performance was
horrible, and other electronics in the car (notably the entertainment
radio and the key dinger) basically freaked out every time the
transmitter got keyed.

Once we changed back to regular through-hole or trunk-lid
antennas, the problems disappeared completely. It all has to do with
decent grounding.

could it be as simple as removing the cell antenna from the exterior
plate(of the radio shack cellular version) and reattaching a 2.4 ghz
omni?


No. The coupling box of any glass-mount antenna contains a
frequency-sensitive matching circuit. A circuit designed for cellphone
frequencies will not work with WiFi freqs.

If you need a mobile WiFi antenna, and you don't want to drill
holes, use a magnetic mount.

Happy tweaking.

--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
(Known to some as Bruce Lane, ARS KC7GR,
kyrrin (a/t) bluefeathertech[d=o=t]calm --
www.bluefeathertech.com
"If Salvador Dali had owned a computer, would it have been equipped
with surreal ports?"
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Old January 12th 06, 12:28 PM posted to rec.radio.amateur.homebrew
xpyttl
 
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Default glass-mount omnidirectional antenna?

"Dr. Anton T. Squeegee" wrote in message
...

If you're serious about decent peformance, stay away from glass
mount antennas for anything other than receive-only. They're worse than
useless for transmitting.


I think you better stick to the paintings. Anecdotal evidence is worse than
no evidence. Just because one manufacturer's antenna was junk doesn't mean
they all are. There does seem to be considerable variability in glass mount
antennas, though. Some people report good results, others horrible, and
little in the middle. Still, at 2.4G I'd personally be a bit suspicious of
glass mount.

However, OP has another problem. Nobody has mentioned feedline loss. The
wire carrying the signal to the antenna, even with a good SWR, can be a real
source of loss, especially at 2.4G. Cable which has a low loss at that
frequency is available, but it is expensive and hard to get. As someone
else has suggested, it may be better just to keep the antenna in the
vehicle.

I would also caution OP, presuming he is in the U.S., there are pretty
significant limitations to what he can do legally with WiFi. Besides power
limitations, there are a number of other limitations designed to protect
other users of that spectrum (including amateurs). WiFi is a tertiary user
of that spectrum, and you are REQUIRED not to interfere with the other
users. You are also required to accept interference from the primary and
secondary users.

Now the odds that you will be called on interference either way are pretty
small, but recognize that in general modifications, even something as simple
as an external antenna, are disallowed by the regulations.

...


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Old January 14th 06, 03:07 AM posted to rec.radio.amateur.homebrew
Spajky
 
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Default glass-mount omnidirectional antenna?

On Thu, 12 Jan 2006 07:28:13 -0500, "xpyttl"
wrote:

However, OP has another problem. Nobody has mentioned feedline loss. The
wire carrying the signal to the antenna, even with a good SWR, can be a real
source of loss, especially at 2.4G. Cable which has a low loss at that
frequency is available, but it is expensive and hard to get.


an alternative would be using TVSat 75ohm cable & connectors properly
lenght cut to mirror Z from source 50ohm to antenna (taking care of
cable velocity factor & unpair 1/4 multiple wave lenght proper cut);
this way is cheap ...
--
Seasons Greetings & Regards , SPAJKY ®
mail addr. @ my site @ http://www.spajky.vze.com
more than 3y - "Tualatin OC-ed / BX-Slot1 / inaudible setup!"
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Old January 15th 06, 09:29 AM posted to rec.radio.amateur.homebrew
Saandy , 4Z5KS
 
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Default glass-mount omnidirectional antenna?

Hi Kevin:
the main reason you didn't find one is the glass losses!
at 2.4GHz, the loss of most kinds of glass winshields are made of, is
so hi as to defeat operation!
using a different base, such a cellular one will work, since it has a
high pass filtering characteristic, but like I said, the glass itself
can prove to be an insurmountable hurdle.
Saandy 4Z5KS

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