| Automotive radar is a key sensor of automotive intelligent safety systems.With the increasing requirements of radar detection range resolution,speed resolution,angular resolution,and radar volume,research on millimeter waves is gradually moving to the higher frequency at 79 GHz.At present,the 76-81 GHz has been opened to the automotive radar business for applications such as high-precision positioning,target detection imaging,and autonomous driving.The available bandwidth of automotive radars has been several times greater,and the resolution of automotive radars has been increased several times.As an indispensable part of the radar system,the antenna is the front-end device of the automotive radar.The antenna is a major research topic as it has huge impact on the size,cost and performance of an automotive radar.This thesis focuses on the design of substrate integrated waveguide(SIW)slot array antennas used in millimeter wave automotive radar.The main work of this thesis is as follows:First,this thesis summarizes the development of automotive radar antennas and SIW slot arrays.Then,the structure and design principle of the SIW are summarized.The design methods of the SIW slot array antenna in the form of standing wave and traveling wave are expounded.The theoretical foundation is consolidated.Subsequently,two types of narrowband SIW slot array antenna with longitudinal slots operating at 79 GHz were designed.The design idea of radiation pattern synthesis is studied.By applying the Chebyshev pattern synthesis method,the sidelobe of the narrow-band SIW slot array antenna can be controlled.The design method of the SIW feed network is also studied.Following the 79 GHz automotive radar’s requirements for antenna operating bandwidth,beam width,sidelobe level,and beam pointing deviation,a broadband standing wave SIW slot array covering 76 ~ 81 GHz was designed.The genetic algorithm was applied to optimize the sidelobe level and impedance bandwidth of the antenna.At the same time,the broadband switching structure of the SIW and the standard waveguide was designed.The wideband SIW slot array is processed and tested.The experimental test results and simulation results basically match.The antenna performance meets the requirements of 79 GHz automotive radar.According to the requirement of 79 GHz automotive radar for angular resolution,a 3T4 RMIMO array antenna is designed.The method of modifying the antenna azimuth pattern using an additional passive parasitic line array is studied. |
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