Research On Millimeter Wave Radar Array Antenna

With the upgrading of people's living standards,small passenger cars as a general commodity have gradually entered every household,and the safety of passenger cars has increasingly attracted the attention of consumers.Millimeter wave radar plays an important role in the daily use of active safety devices.It is widely used in forward collision avoidance,lane change assistance,blind spot detection and other scenes.According to the different application of vehicle millimeter wave radar,there are different design requirements for antenna.In this paper,two kinds of high gain array antennas for forward collision avoidance and one kind of wide beam array antenna for passenger car collision avoidance angle radar are designed respectively.The specific research contents are as follows1.The design of SIW array antenna for 77GHz forward vehicle long distance collision avoidance radar.The forward collision radar antenna uses SIW(subtrateintegrated waveguide)technology which has both low loss characteristics of metal waveguide and easy integration of plane transmission line.(1)8×10 array design.According to the HFSS parameter extraction method of SIW single slot,the radiation element parameters of 1×10array are extracted.The current amplitude distribution of each slot of 1×10 linear array is determined by Taylor synthesis method to achieve the performance of low sidelobe.The designed 1×10 element slot array is used as the radiation sub array of 8×10 antenna array.The feeder structure of 8×10 array is designed by tree network composed of Y/T type unequal power divider.To reduce the side lobe level of the plane array SLL effectively,the power distribution of the output port of the 8×10 array feed network is designed by Taylor synthesis method.The overall dimension of the array is 24mm×42mm,the array is S₁₁<10d B in 76.5GHz?77.5GHz frequency band,11.9°and 14.2°in E-Plane(azimuth)and H-plane(pitching plane),respectively.The side lobe level SLL<-20.2d B,and the antenna gain is 23.4d B in the 76.5GHz?77.5GHz band.(2)To reduce the overall size of radar antenna,a small 8×10 array is designed.The compact direct eight feed network is used to feed the array,and its overall size is 22.4mm×31mm.Compared with the tree feed network,the area of the array is reduced by 30%.The impedance bandwidth of miniaturized array is76.4GHz-77.7GHz,and the maximum gain is 23.6d B and the side lobe level SLL is less than-19.7d B.Both antennas meet the requirements of the vehicle forward collision avoidance radar for antenna high gain,narrow main lobe and low sidelobe.2.77GHz anti-collision angle radar antenna design.The angle radar used in vehicle collision avoidance needs wide beam angle coverage to meet the needs of wide angle detection.The 3d B beam width of single microstrip feeder array in azimuth plane is in the range of 60°to 80°and can not meet the needs of wide beam.To realize wide beam coverage of microstrip array antenna in horizontal plane,a double-layer wide beam antenna is designed.The antenna adopts a double-layer structure.Parasitic patch and dielectric substrate are loaded on the top of the 10 element microstrip series fed array.The electromagnetic coupling between the microstrip series fed antenna and the parasitic patch expands the 3d B beam width of the antenna azimuth plane(H plane).The measured results show that the 3d B beam width(HPBW)of the double-layer wide beam antenna azimuth plane is 134.6°and the gain can reach 10.6d B and the sidelobe level SLL=-19.8d B The simulation results of impedance bandwidth are 1.5GHz(76.2GHz?77.7GHz),and the actual test impedance bandwidth of processing antenna is 1.8GHz(75.8GHz?77.6GHz).The actual test and simulation results are consistent,which can meet the requirements of vehicle angle radar antenna.