| With the rapid development of unmanned driving technology,the requirements for vehicle environment perception are getting higher and higher.77 GHz millimeter-wave radar has become one of the core sensors of unmanned vehicles for its high accuracy,small size,light weight,long measurement distance,moderate cost and good anti-interference ability.The antenna system is the important component of the millimeter wave radar,and its performance directly affects the detection capability of the radar.Therefore,it is necessary to design the structure to improve the performance of the millimeter wave radar.Aiming at the specific performance requirements of the automotive rearward detection corner radar,this paper has carried out systematic research work on antenna array design,feeder waveguide design,antenna array coupling suppression and radome design for high-gain and wide-angle antennas.The specific research content is as follows:(1)In response to the requirements of high-gain and wide-angle of automotive rear millimeter-wave corner radar,the antenna array is designed in a given design space.A 10-array element series-fed microstrip linear array is designed and optimized,and the low sidelobe is obtained by controlling the patch width to adjust the excitation amplitude distribution using Taylor synthesis method;The grounded coplanar waveguide used for feeding is analyzed,and its structural parameters are optimized;An antenna array with two transmitting and four receiving antennas and grounded coplanar waveguide transmission lines from the chip to antennas are designed.The designed antenna operating frequency band covers 77-78.5GHz,the gain of the two transmitting antennas is greater than 13 d Bi,and the azimuth beam width is greater than 90°.(2)Aiming at the problem that the mutual coupling between the transmitting and receiving antennas of millimeter-wave radar affects the detection capability of radar,the electromagnetic band gap structures are used to suppress the mutual coupling of antennas and improve the transmission and reception isolation.The principle of mutual coupling suppression of the EBG structure is studied,and an L-shaped slotted EBG structure is proposed using slot loading technology and the influence of different structural parameters on its surface wave suppression band gap is analyzed.and the isolation between the transmitting and receiving antennas has been improved.The transceiver isolation of antenna array in the working frequency band is improved after adding the proposed EBG structure,and a certain mutual coupling suppression effect is achieved,the return loss and pattern of the antenna are not greatly affected.(3)In view of the complex working environment of the automotive millimeter-wave radar antenna,the radome is designed to ensure the stable operation of the millimeter wave radar.First,the common radiating materials and structure forms of radome are analyzed.Then a solid-walled flat-panel radome is designed and optimized.The radome has good wave transmission performance and has no obvious impact on the radiation beam.The simulation analysis of the radome is carried out,and the result shows that the designed radome has no obvious damage after falling,and it has good electrical performance and good structural strength. |
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