Radar system using quadrature signal

A radar system comprising:

• a quadrature push—push oscillator for generating four harmonics with a 90-degree phase difference from each other, and for producing two-balanced 2nd harmonic signals from the harmonics;
• a first coupler block for radiating one of the 2nd harmonics through an antenna;
• a second coupler block for terminating the other 2nd harmonic to ground;
• a power combiner for combining a transmitted signal that is leaked from the first and second coupler blocks with the received signal that is radiated through the antenna;
• a 90-degree phase shifter for shifting the phase of the output signal from the power combiner by 90 degrees;
• a first quadrature mixer for mixing an in-phase harmonic signal inputted from the quadrature push—push oscillator with the output signal from the power combiner, and outputting a first baseband signal;
• and
• a second quadrature mixer for mixing a quadrature-phase harmonic signal inputted from the quadrature push—push oscillator with the output signal from the 90-degree phase shifter, and outputting a second baseband signal.