... FME 12dbi Gsm Receiver and Gsm Antenna booster GSM eceiver : Frequency:850-900-1800-1900MHzGSM antenna: Frequency:850-900-1800-1900MHzGain: ... :<1.5 : 1Impedance: 50Ω GSM signal receiver plus antenna, is used for mobile phone signal appears unstable, call ... first step: the signal receiver and GSM antenna is connected to Step Two: Do you think the ... is needed. 12dbi Gsm Receiver and Gsm Antenna booster