An Array Antenna for Both Long- and Medium-Range 77 GHz Automotive Radar Applications

A novel array antenna with a flat-shoulder shaped radiation pattern is proposed as the transmitting antenna for 77 GHz automotive radar application. When it is used in an automotive radar comprising one transmitter and multiple identical receivers, it can meet the demands of both long-range and medium-range detections without switching the operation mode back and forth between the long-range radar scenario and the medium-range radar scenario. The proposed antenna concept is fully introduced to explain its mechanism. An unconventional array was synthesized to achieve the desired flat-shoulder shaped radiation pattern. Prototype of the proposed array antenna was also designed according to the array synthesis result, which consists of several linear series-fed patch arrays and a substrate-integrated waveguide power and phase distributing network. Fabrication and measurement of the prototype array antenna were completed, showing a good agreement between the measured data and the synthesized as well as the simulation results, thereby validating the design.