Transmitter/receiver apparatus

The transmitter/receiver apparatus as described compri­ses a local oscillator (2) for generating a local oscillation frequency at a predetermined position between a transmit and a receive frequency band; a transmit frequency converter (6) for converting a transmit inter­mediate frequency band into the transmit frequency band based on the local oscillation frequency such that a transmit image frequency band of the transmit fre­quency band does not overlap the receive frequency band; and a receive frequency converter (5) for converting, based on the local oscillation frequency, the receive frequency band into a receive intermediate frequency band. This receive intermediate frequency band does not overlap the transmit intermediate frequency band, such that a receive image frequency band of the receiver intermediate frequency band does not overlap the transmit frequency band. This provides for a miniature and inexpensive transmitter/receiver apparatus which is satisfactorily applicable to microwave band communi­cations even if the isolation between discrete circuits is insufficient.