| The thesis is made with scientific research projects,and the automotive millimeter wave radar antenna array is researched.Firstly,the related concepts used in this thesis are explained,the research status and existing problems are discussed,the background and significance of the topic selection of automotive millimeter wave radar antenna is expounded,and the relevant basic theories used in this thesis are discussed;secondly,the automotive millimeter wave radar antenna arrays are researched.The specific research work is as follows:1.Automotive Millimeter Wave Radar Microstrip Antenna Array According to the design requirements of high gain and low sidelobe,the microstrip antenna array of automotive millimeter wave radar is developed.The method of microstrip antenna array is used to achieve the radiation characteristics.The Chebyshev power distribution is used in line array to reduce its sidelobe level,and compared the same amplitude distribution with Chebyshev distribution.Then the feed network which meets the power distribution of Chebyshev distribution is designed and used for array feed.Based on the designed antenna array model,an engineering prototype is developed and tested.The designed antenna array can achieve the maximum gain of 23.9d Bi,the sidelobe level of-20.2d B in H-plane,and the 3d B beam width of 10.2°,which can meet the design requirements of 77 GHz automotive millimeter wave radar microstrip antenna array.2.Automotive Millimeter Wave Radar Microstrip Comb Antenna Array The microstrip comb antenna array of automotive millimeter wave radar is researched.By changing the array mode of microstrip antenna array,the size of antenna array is reduced while the number of array elements is kept constant,and the sidelobe level is reduced by Chebyshev power distribution.In order to connect the antenna array with the millimeter wave test system conveniently,a waveguide to microstrip conversion structure based on the substrate integrated waveguide(SIW)technology is developed.The test results of the engineering prototype show that the impedance bandwidth of the developed antenna array covers 76.0~77.0 GHz.In the impedance bandwidth range,the maximum gain of the antenna array is 22.7d Bi,the sidelobe level of H-plane is-20.2d B and the 3d B beam width is 9.8°,which fully meet the design requirements.The antenna array improves the problem that the traditional microstrip antenna array needs large installation platform space.3.Automotive Millimeter Wave Radar Beamforming Antenna Array Based on the beamforming theory,the beamforming antenna array of antomotive millimeter wave radar is designed.The equal amplitude and unequal phase feed is adopted for the antenna elements with unequal spacing to obtain the shoulder pattern which can replace the conventional pattern of dual antenna array.In order to reduce the loss,SIW technology is used to design the feed network.Through the research,design and combination of 1/3 unequal power divider,1/2 equal power divider and phase shifter based on SIW technology,a six equal amplitude and unequal phase power divider is developed and connected to the antenna array element through SIW microstrip conversion.The antenna array achieves the maximum gain of more than 18.5d Bi and the gain of more than 6.0d Bi in the range of-40°~20° and 20°~40° radiation angles,which provides a new scheme for the existing automotive millimeter wave radar antenna array.Finally,the research work that needs to be carried out further are pointed out. |
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