A low cost 24-GHz FMCW radar for automobile application

A 24-GHz frequency modulation continuous-wave radar sensor with a novel type, low-profile, and low cost array antenna, is presented. A Gunn voltage-controlled oscillator and the driver amplifier MMIC act as transmitter and a Rat-race hybrid mixer act as receiver, respectively, connected by a hexferrite microstrip circulator. A 100-patch microstrip antenna array with a high gain and a narrow beam width operates at radar system in k-band. This antenna is made by 10/spl times/10 elements (90/spl times/90 mm/sup 2/) ,the E-plane has the 3 dB beam-width /spl plusmn/ 3.5/spl deg/, and H-plane has a slightly broader beam-width /spl plusmn/ 7/spl deg/. The gain measured at 24 GHz is 22 dB.