To provide a smaller radar system having a simple structure with as small number of component parts as possible at a lower cost as compared to conventional ones. A radar system 1 including a 3 dB coupler 5 having four terminals, and a pulse generator 8. A first terminal 51 of the 3 dB coupler 5 is supplied with an output signal from a high frequency oscillator 2 while a second terminal 52 of the 3 dB coupler 5 is connected to a transmitting and receiving antenna 4. Third and fourth terminals 53 and 54 of the 3 dB coupler 5 are connected to two-state devices 6, 7, respectively, which are in impedance mismatched only for a predetermined period of time to totally reflect the signal from the 3 dB coupler 5 and are in impedance matched during the time period other than the predetermined time to direct a signal from the 3 dB coupler 5 to a subsequent electronic circuit. The pulse generator 8 causes the two-state devices 6, 7 to be impedance mismatched at the time of transmission and causes the two-state devices 6, 7 to be impedance matched at the time of reception.