One embodiment relates to a coupler that can be used in a radar system. The coupler includes differential ports, an antenna port, a receiver port, a local port and a transmission path. The differential ports are configured to receive a differential signal. The antenna port is configured to output a transmitted signal and to input a received signal. The transmitted signal is derived from the differential signal. The receiver port is configured to output a portion or version of the received signal. The local port outputs a local signal, which is also derived from the differential signal. The transmission path is coupled to the differential ports, the antenna port, the receiver port and the local port. The transmission path typically has a length selected to derive or output the signals at the above ports.