A front end module for a wireless transmission/reception device has two antennas and two signal paths connected thereto. A mismatch in the antenna is identified by monitoring the transmitted power and the reflected power in the active and passive signal paths and using the powers in a controller to generate a control signal for the antenna tuner. In this case, decreasing isolation between the first and second antennas and the first and second signal paths is identified, and is compensated for using different devices, in order to ensure faster and safer antenna matching.