According to a first aspect of the present disclosed subject matter, a method for detecting foreign objects by a host transmitter inductively coupled with a repeater, the method comprising: obtaining a Q-factor from a receiver placed on the repeater; measuring a decay pattern of at least one joint resonance frequency (JRF); determining a Q-factor of the repeater based on the decay pattern; and determining foreign object presence based on the Q-factor of the repeater and a corrected Q-factor obtained from the receiver.