rf combiner for different frequencies

[adnan012]

hi,

What is the purpose of using rf combiner in GSM infrastructures (BTS) . Is it possible to add two different frequencies, f1 at 915MHz and the f2 960MHz ,using combiner and terminate it on single antenna.

 

[kh4n]

if u have 915MHz at one band and 960MHz at he second, you can combine those two signal with a combiner that can cover both frequencies, and send them to a single antenna.

 

[tony_lth]

But combiner has big insertion loss. At least 3dB for normal microstrip combiner. So switch is preferred.

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But combiner has big insertion loss. At least 3dB for normal microstrip combiner. So switch is preferred.

 

[RCinFLA]

You would use a duplexer filter for the 45 MHz separation. Back in old analog days all cellphone had them. Today CDMA phones have them.

For GSM BTS it allows Tx's and Rx's to happen simultaneous to service multiple callers on all Tx and Rx slots.
**broken link removed**

 

[adnan012]

what is the purpose of combiner in case of power combining. Suppose there are two amplifiers both have output power of 10 watts.IF there is 3db insertion loss , it means there is half power loss for each amplifier. At the output of the combiner there will be 10watts power . What is the concept of adding power or implementing balanced amplifier using combiner?

amplifier A 10 watts --- 3db loss ---5 watts
>>>>>> 10 watts
amplifier B 10 watts --- 3db loss ---5 watts