Want to Build a GSM 900/1800 Signal Booster

Maybe you could contact some of the many manufacturers and ask them for a schematic.

I seriously doubt if you can build one as the components are Surface mount and really small and the circuit boards are speacial to minimise interference.

try googling mobile phone boosters there is a lot of ready made products out there

GSM 900/1800 signal booster increase your mobile phone signals and its working rang is 800 square meter. To construct a gsm 900/1800 signal booster create contact for some generative they gives you some schematic.