glass-mount omnidirectional antenna?
 

I used to have a in-car cell phone system and it had a glass-mount
antenna which didn't require drilling. Basically, there was
coax(conntected to the cell) to a plate that stuck to the inside of the
rear window. Then on the outside of that window was another plate with
the antenna attached to it. You can buy these a radio shack I noticed.
I've also seem the same done for XM/Sirius Satellite radio.

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,
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? Or maybe I could modify the existing cell antenna to the correct
1/2 wavelength of 2.4ghz?

Your suggestions / help / tips are appreciated.

-Kevin

glass-mount omnidirectional antenna?
 

On 10 Jan 2006 20:01:17 -0800, "kevincw01" wrote:

I used to have a in-car cell phone system and it had a glass-mount
antenna which didn't require drilling. Basically, there was
coax(conntected to the cell) to a plate that stuck to the inside of the
rear window. Then on the outside of that window was another plate with
the antenna attached to it. You can buy these a radio shack I noticed.
I've also seem the same done for XM/Sirius Satellite radio.

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,
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? Or maybe I could modify the existing cell antenna to the correct
1/2 wavelength of 2.4ghz?

Haven't seen a 2.4G unit, which doesn't mean they aren't out there.

But the through-glass coupling is fairly narrowband and incorporates tuning
elements. The 800/900 MHz units would present a shocking SWR at 2.4G.

glass-mount omnidirectional antenna?
 

sorry to have to ask but what is SWR? My guess is sound to [somthing]
ratio?

glass-mount omnidirectional antenna?
 

On 10 Jan 2006 23:57:15 -0800, "kevincw01" wrote:

sorry to have to ask but what is SWR? My guess is sound to [somthing]
ratio?

Standing wave ratio. It is a measure of how well (in this case) the antenna
system accepts the energy sent to it up the transmission line and radiates it,
compared to reflecting it back to the source transmitter. The transmission line
should be 50 ohm coax in your case. If the tranmission line/system has serious
impedance variation or discontinuity, power is reflected back to the source
rather than passing along the line.

As the through-glass coupling system employs frequency-sensitive tuned circuit
elements, a substantial change in frequency as you suggest will certainly create
a serious impedance discontinuity. Overall transmission efficiency pooter-
antenna would be very poor as a result. You may well find that a decent 2.4G
antenna on the pooter inside the vehicle is more efficient.

glass-mount omnidirectional antenna?
 

looks like i will have to go that route then since I have (so far) not
come across anything for the 2.4G frequency. Either that or drill a
whole in the vehicle.

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?"

glass-mount omnidirectional antenna?
 

In article .com,
says...

sorry to have to ask but what is SWR? My guess is sound to [somthing]
ratio?

Oh dear... Someone didn't pay attention in license class...

SWR = Standing Wave Ratio. Put simply, it has to do with how good
of a load the antenna presents to the transmitter, and how efficiently
it will couple the transmitter's energy to the atmosphere.

It needs to be as close to 1:1 as possible. If you're using a
wattmeter to measure things, you want to see as low as possible a
reading in the 'reflected' mode and as high as possible in the
'forward' mode.

Here are some more details.

http://www.hamquick.com/tutorial_index.php?id=20

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?"

glass-mount omnidirectional antenna?
 

i have an excused, i dont have a license :)

glass-mount omnidirectional antenna?
 

On Wed, 11 Jan 2006 22:33:28 -0800, Dr. Anton T. Squeegee
wrote:

In article .com,
says...

sorry to have to ask but what is SWR? My guess is sound to [somthing]
ratio?

Oh dear... Someone didn't pay attention in license class...

SWR = Standing Wave Ratio. Put simply, it has to do with how good
of a load the antenna presents to the transmitter, and how efficiently
it will couple the transmitter's energy to the atmosphere.

Nothing to do with coupling the Tx energy to the "atmosphere". Terminating the
line in a resistor of the line's charactertistic impedance will present a nice
SWR and radiate very little.

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.

...