GSM antenna output impedance

[alzomor]

gsm impedance antenna

Hi

I am using a GPRS/GPS module
I face a strange problem Suddenly the GPRS is not working and when I measure the impedance on the antenna connector I found it equals to 1.2 ohm, I m expecting to see 50 ohms
am I true?
dose that means that the LNA and PA has burnt out due to ESD?

Salam
Hossam Alzomor
www()i-g()org

 

[GSM Man]

How are you measuring the impedance?

 

[alzomor]

I am using ohmmeter

 

[GSM Man]

I am using ohmmeter

Then you're not measuring the impedance - you're simple measuring the DC resistance of the output. For that, 1.2 ohms is not unreasonable.

 

[alzomor]

hi

do you know exactly what should be the value to be measured by ohm meter on antenna output?

 

[vfone]

Hmmm! You are using the ohm-meter to measure the impedance!?
I was so stupid to pay $50.000 for a Network Analyzer when actually a $10 multi-meter would be fine.

 

[alzomor]

Hi

as you can see the ohmmeter was not suitable for doing the JOB.
but I think network analyzer is so expensive also .
what about using RLC meter?

Salam
Hossam Alzomor

 

[Chinaski]

RLC meters make measurements at low frequencies. As vfone said, you _do_ need a VNA for measuring the impedance of an antenna at GSM freqs. Of course, you can use a SWR meter (cheaper solution) but in that case you will not not measure the input impedance but something related with.
Good luck

 

[GSM Man]

I face a strange problem Suddenly the GPRS is not working... and when I measure the impedance on the antenna connector I found it equals to 1.2 ohm, I m expecting to see 50 ohms

I feel you may be wasting a lot of your time trying to measure the radio's impedance. The module is either good or bad, trying to measure the impedence isn't doing you much good. If you use a different module with your SIM card, does it work? Is it only GPRS that doesn't function, or can you not connect to the network? I've destroyed a few modules myself, and its always been fairly easy to determine if its working or not.