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Duplexer for my GSM active Repeater

roltex_rohit123

Oct 12, 2009
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I am currently working to finish my project. I need to construct a duplexer for of 100db isolation at 900MHz frequency range. any suggestions/ help?
 

davenn

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Sep 5, 2009
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I am currently working to finish my project. I need to construct a duplexer for of 100db isolation at 900MHz frequency range. any suggestions/ help?

you are probably never going to get 100dB isolation

the best you could expect even for something commercial would be around the 40 - 60 dB
and the 60dB would be an extreme limit. 40 - 50 dB would be an excellent expected result

Dave
 

roltex_rohit123

Oct 12, 2009
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you are probably never going to get 100dB isolation

the best you could expect even for something commercial would be around the 40 - 60 dB
and the 60dB would be an extreme limit. 40 - 50 dB would be an excellent expected result

Dave

the gain in the antenna would be around 50db so is it ok with 40-50db isolation?
 

davenn

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the gain in the antenna would be around 50db so is it ok with 40-50db isolation?

50dB gain? what sort of antenna are you using a very large greater than 20 metre diameter dish ? :)

Dave
 
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davenn

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the gain is from the module. I have an old dish antenna from my satellite TV diameter 1meter

a module is that the receive module ? transmit module ?
what is your intended transmitter output ?


a 1 metre dish will have a ~ 14 - 15 dBi gain at 900MHz

you need to be more accurate in you descriptions so that misunderstandings dont happen :)


a 20 element yagi will give ~ 17dBi gain at 900 MHz
2 of them in phase will add another 3 dB of gain

cheers
Dave
 
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