A portable electronic device comprises a wireless receiver unit for receiving a wireless signal from a transmitting device, the wireless receiver unit comprising an antenna receiving an electromagnetic signal and providing a received electric input signal, and a receiver providing a recovered electric signal from the received electric input signal, and an impedance matching circuit matching the electric impedance of the antenna to the receiver, the receiver comprising a gain stage comprising an Automatic Gain Control unit automatically determining an AGC-gain value for application to an AGC-input signal to provide an appropriate signal level when the level of said AGC input signal is in a range between a minimum and a maximum signal level corresponding to maximum and minimum AGC-gain values, respectively. The portable device further comprises a control unit receiving the AGC-gain value and providing a control signal depending on said AGC-gain value to the impedance matching circuit.