| With the rapid development of wireless mobile communication technology,there are more and more researches on millimeter wave radar both at home and abroad.With its high resolution and not being easily affected by the weather,millimeter wave radar has been gradually used in many applications scenarios.As the crucial part of the millimeter wave radar system,antenna greatly affects the whole radar system's performance,and its form and complexity,to a great extent,affects the costs of the system.Therefore,it is very important to design suitable antennas for different millimeter wave radar applications.This paper focuses on the research and design of millimeter wave radar antennas.The main work is as follows:In terms of the application of long-range detection of millimeter wave radar,a high-gain and narrow beam antenna array was designed with the form of a low-cost,easy-to-integrate microstrip.By analyzing the theory of the microstrip antenna,a rectangular microstrip antenna unit was designed and then made up a 1×16 element linear array.The Chebyshev synthesis method was used to optimize the sidelobe level.The maximum gain of the 1×16 element linear array is 17.0d B and the sidelobe level is-16.6d B.In order to further increase the gain of the antenna,a 4×16 element antenna array is formed with a serial-parallel feed mode,which reduces the overall complexity of the antenna.The array gain is 23.3d B,and the E-sidelobe level is-20.1d B.Through an utter research of the radiation theory of the microstrip line and the design method of the comb-line antenna array,a comb-line antenna array with full wave spacing was designed.By changing the element spacing to half wavelength,the gain and sidelobe level of the antenna array were improved,and the overall structure was more compact,which improved the oversized installation platform of the traditional microstrip antenna array.The 8×10 element comb-line antenna array gain is 22.6d B,and the E-sidelobe level is-18.5d B.At the same time,a 1×9 element comb-line antenna array with a wide frequency band was designed for the application of close-range and high-resolution millimeter-wave radar.By adopting multiple radiating elements with different impedances,the antenna bandwidth has reached 70-85 GHz,which greatly improves the resolution of millimeter wave radar.Aiming at the application scenarios of mid-range and wide-angle in the millimeter wave radar,a novel gap waveguide structure was used to design a 4×4 Butler matrix and a 1×8 element slot antenna array.Then a 4×8 element multi-beam antenna array was developed.The antenna array can switch four beams,covering an angular range of ±45°.The gap waveguide structure has low loss and needs lower processing accuracy,so the multi-beam antenna array can meet the needs of practical applications in terms of performance and the possibility to be processed.Finally,a method for testing the overall pattern of the on-board radar antenna is designed,The performance of the rectangular microstrip antenna array was tested in the microwave anechoic chamber.The testing results agreed with the simulation,indicating that the antenna can meet the application requirements. |
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