PURPOSE: To enable signal detection in proper low frequency and to simplify hardware by generating both of a transmission signal and the signal of a receiving station part oscillator (LO) on a common micro-carrier wave and forming non-zero receiver intermediate frequency.

CONSTITUTION: A frequency synthesizer 54 converts the reference frequency from a reference oscillator 52 to a desired microwave region and enables the selection of a frequency region necessary for certain specific application. The signal modulated in its waveform by a digital waveform generator 56 so as to respond and synchronize to a parameter control command and a clock signal 58 is divided by a coupler 60 and one signal is outputted to a transmitter or an antenna through a transmission pulse gate circuit 62 and an output amplifier 64 and other one signal is sent out to a receiver 70 through an LO waveform gate circuit 66. Since an excitation part 50 generates desired micro-carrier wave frequency, chirp or extension frequency modulation can be adapted to the frequency. Therefore, additional hardware becomes unnecessary.