A Novel 24-GHz Air-filled Cavity-backed Slot Antenna Array with Out-of-phase Power Divider for Automotive Radar System

A novel 24-GHz cavity backed slot antenna with out-of-phase power divider based on multilayer air-filled print circuit board (PCB) for automotive radar is presented. By etching the bow-tie slot and rectangular slot on the antenna element, the two resonant frequencies at 23.45GHz and 24.15GHz are stimulated. For the antenna element, the measured operating frequency band is 23-25.01GHz and the maximum measured gain is 7.0SdBi. And then, the antenna array with 16 antenna elements is proposed. The microstrip-to-slotline power divider with 180°phase difference is designed to compose the feeding network. According to the measured results of the antenna array, the impedance bandwidth is from 23.22-25.03GHz and the maximum gain is 14.83dBi. In addition, the front-back ratio (F/B) is larger than 25dB.