GSM 900 Repeater design

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zac79x

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First hello to all, it should be my first post here...
I'm "trying" to design a GSM 900 repeater with this scheme:
directive antenna --> LNA --> AMP+AGC --> PA --> omni antenna
directive antenna <-- AMP <-- AMP+AGC <-- omni antenna
The antennas are the same, i'm using diplexers on every side.
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 informations ?
 

Hi,

U question is to general!
u rest a lot of parameters

when u say weak signal how much do u mean


In general (i will put some parameters of my system) :
u will receive from BS to Repeater between -60dBm ÷ -90dBm.
Your PA suppose to be about 30dBm (again all numbers depend on distance and of course mobile channel parameters like do u transmit LOS etc...)
One of the most important parameters is DL total + UL total Gain suppose to be less then isolations of the both diplexers (from tx to rx) by factor of 12dB at least.

David

Added after 1 minutes:


In my system:

DL gain was Glna=60dB, G_PA=30dB
UL gain was Glna=45dB, G_PA=30dB

David
 

    Z

    zac79x

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Sorry for the missing parameters, but it's a new field for me. Some data:
Uplink 890-915 MHz, Downlink 935-960MHz
I'm thinking about a class B or hybrid broadband repeater. The service antenna should be capable of a near field coverage of about 20m*20m. This should be a BDA for home or office use in GSM band only.
I have problems finding suitable SAW filters, so i'm not able to obtain high TX-RX isolation...
For the PA stage i'm trying to use RF2104, for the LNA the AVAGO'S ATF33143. Interstage amps use broadband MMIC or BJT transistors.
Admitting I receive -90dBm at the donor antenna, and I want a near field coverage of about 20m+20m, are -10dBm at the service antenna enough ?
 

Hi,

Please expain: I want a near field coverage of about 20m+20m.

David

Added after 6 minutes:

Hi,

About the saw filters
try to look for them at: EPCOS and Sawtec (triquint) (may be that i made a mistake with the names but they PRETTY SURE THEY WILL HAVE IT!)

David
 

    Z

    zac79x

    Points: 2
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I made a mistype, i meant 20m*20m field coverage near the service antenna (supposing an omnidirectanional antenna). The donor antenna has to placed with a sufficient distance from the service antenna.Your answers and suggestions are appreciated!
 

Okay,

If u need something else please let me know!

David
 

HI to ALL,
Can anyone tell me the Schematic of GSM Repeater.plz reply me at:sykh84@msn.com
 

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