| Recently, lots of radar systems are used in different kinds of fields, playing an increasingly important role in reconnaissance, meteorological observation, precision guidance and collision avoidance systems. Millimeter-wave radar is being a common method of modern vehicle detectors with its high resolution, small size antennas and components, especially the ability to adapt to the harsh environment. In a typical radar system, the transmitter waveform of FMCW(Frequency Modulated Continuous Wave) radar is simple, high accuracy and good for processing digital signal. What’s more, the Homodyne receivers take part of transmitted signal as local signal, so that it costs little to modulate and design, which is gradually replacing the infrared and ultrasonic radar used for collision avoidance system, being the preferred collision avoidance radar.This thesis is based on project of "Ka-band automotive anti-collision LFMCW radar" to study the millimeter wave front-end of the train anti-collision radar. As a key part of radar,the millimeter-wave front-end mainly achieves frequency conversion and power amplification. How to realize the function of each component and the overall system is a major difficulty for the millimeter-wave front-end system, and it’s aslo difficult to reduce the size of millimeter-wave front-end system for the automotive anti-collision radar. Pursuing the indicators while reducing the size as much as possible is difficult for millimeter-wave front-end, and it’s also the highlights of the entire radar system. By addressing these two problems, this thesis achieves the indicators of millimeter-wave front-end system well. The main contents are as follows:1. Based on the indicators of LFMCW automotive anti-collision radar, the indicators of millimeter wave front-end system are discussed and determined, then the millimeter-wave front-end system is given by contrast two kinds of common radar structure. The system simulation is complete by ADS, and the simulation results meet with the design requirements;2. According to the system requirements, designing the functional modules, which can not only achieve the function of each component but also meet the needs of the system’s budget, laying the foundation for the millimeter-wave front-end system;3. The scheme of millimeter-wave front-end system is show, and the analyze and solutions of electromagnetic compatibility problems encountering in the process of testing is also given. Finally, the test results of millimeter-wave front-end system are show;4. Based on the LCP material, several multilayer structure passive components are designed. It not only meets with the requirements of the system, but also reduces the size of passive components, some results of the research have been published in 2013 International Conference on Computational Problem-Solving(ICCP 2013), some results of the research have been submitted to Microwave and Optical Technology Letters(MOTL). Several multilayer transition structures are designed, which are benefit for the miniaturized integrate of millimeter wave front-end system;5. To improve the performance of the millimeter wave front-end systems and reduce the whole size. The better design based on the LCP material has finished, and the test results show that the new millimeter-wave front-end system meet with the requirements of LFMCW radar system. |
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