Hi everyone ,I want to design a device called "GSM repeater" which convert 900 MHZ to 1800 MHZ ,since there is a network problem in my local area where I live I have decided to design this device as an engineer.so I have posted this topic ,any information which will be easy for me to be success acceptable, please help me to work out form that.Welcome you all.

 

Working with Ghz+ circuits is beyond the realm of most beginners (e.g., if you have to ask...)

Did you have a base schematic or guide to work from? It would involve receiving the signal at 900Mhz, demodulating it from the RF, generating a 1.8Ghz carrier, and modulating the demodulated signal onto the new carrier.

Doing this in a way that doesn't corrupt data, send spurious radio waves in non-free bands, and other obstacles is quite a task.

 

I have search from the Google that I have found the circuit diagram but do not understanding the logic of the circuit also can you ex-plane for that from I can get some steps ahead.

 

Look at the Datasheet for the amplifier IC

Read through it, including PCB layout tips, and decide if you are up to the task. It is surface mount only, and needs a 2 layer board with ground plane.

 

I have Read but still have some doubt.How all the graph come in between I am not understood"Gain vs temp" "return loss",(what is input return loss?),etc.can you please ex-plane.

 

Can you give me any circuit diagram or URL for this project by which I can do some steps ahead .

 

OK I Have some information, actually the logic is

directive antenna --> LNA(Low Noise Amplifiers) --> AMP+AGC(Automatic gain control) --> PA(power amplifier) --> omni antenna
directive antenna <-- AMP <-- AMP+AGC <-- omni antenna

So the questions:
How much total gain for the upper side (and bottom side) amps, if i want a functioning repeater for a weak outside signal ?
What power outputs should i use on the PAs ?
Some papers or links to information ?
Thanks.

 

I'd suggest first trying to make an MP3 to FM transmitter that works correctly, preserving stereo, low noise, etc.

The high frequency version would differ in that input would be RF rather than audio, and output is RF. Where it gets complicated is the very high frequency.

See attached to get an insight on the rather intricate details, it's not just a matter of wiring input to output. The PC Board needs to be designed in a special way, as any stray inductance or capacitance will cause the circuit to fail.

 

Hi;
did u make a repeter?
did u find the dfy21r74c1r84bhf data sheet?. if u could find that please give me the link