Attaching 2.4Ghz antenna to a glass mount device

Hi,
I would like to connect a 2.4Ghz antenna to a car glass mount device, such as



[found at www . gadgetcity . com. au/ images/AE5002.jpg[/url] .

I would like to replace the above existing GSM antenna with a wifi antenna. Is it a safe thing to do?
I would like to achieve is a wifi antenna that is mounted externally to my car.

I am using now a magnet-based antenna, but I’m after something permanent and properly mounted.
What should I consider when doing so ?

Thanks,
Kobecube

You likely can turn GSM antenna on the picture into Wi-Fi antenna by making it shorter (cutting off from the top). You can do it if you have measurement equipment (network analyzer).

Thanks, that’s an interesting idea.

However, I already got a 2.4Ghz antenna. All I have to do is to screw it instead of the original 3G antenna.
My question is – is such a replacement is a safe thing to do ?

Cheers

If by 'safe' you mean "will it blow up anything" then the answer is probably no.
The worst is that it may not work as well as you expect if the different antenna increases the SWR. The range will be reduced on transmit.
Depending on the country, GSM frequencies are generally in the ranges of 810MHz, 850MHz, 900MHz and 1800MHz whereas the WiFi frequency is(as you have said) 2400MHz (to keep the units comparable).
As the frequency goes up, so the wave length and the length of a tuned antenna get shorter which is why AndreyG says to cut the length to turn a GSM antenna into a WiFi antenna.
However I understand that you want to do the opposite: turn a WiFI antenna into one for GSM. To do that you really should add loading coils to the antenna to effectively lengthen it. That could be more trouble than it is worth.
Susan