基于不同应用环境的小型宽带天线设计

发布时间：2018-11-17 13:08

【摘要】：随着电子技术的快速发展,人们对无线电系统提出了越来越高的要求,其中,结构的小型化以及功能的多样化将是未来电子系统的重要发展趋势。天线作为无线系统的最前端器件,其设计与系统的整体性能息息相关,因此相关设计技术备受重视。在工程实践中,随着系统应用环境的不同,天线的设计也必须根据指标及需求进行优化,从而充分发挥系统的性能。论文分别针对微波乳腺癌检测系统以及电磁干扰测试系统对于小型宽带天线的需求,介绍了两款宽带定向高增益天线的设计以及优化,包括一个由多层贴片组成的偶极子天线及一个由2×2元圆极化电磁偶极子天线组成的阵列。首先,针对微波乳腺癌检测系统的应用需求,论文设计了一款小型的由多层贴片组成的高增益定向天线应用于检测系统的传感器中。天线由三层介质板组成,其中,第一层为圆形金属贴片,该金属贴片通过一金属的柱子与中间层的激励贴片相连接;激励贴片为一圆形的单极子,通过在单极子贴片上添加分形结构拓展了天线的带宽;第三层为环形寄生贴片,一方面该寄生贴片有助于提高天线的前向增益,另一方面可以增加天线的谐振点从而拓展天线的带宽。天线的整体尺寸为38×13.5mm~2,实测天线的带宽(S11-10dB)为3GHz-4.7GHz,带宽内最大增益达到8dBi。将天线应用于微波乳腺癌检测系统中,利用近似模型进行了大量的仿真以及病灶位置寻找实验,最终验证了天线设计的有效性。其次,针对电磁干扰测试系统需求,论文设计了一款2×2元圆极化宽带电磁偶极子天线阵列。单元采用电磁偶极子结构,通过高精度的数控机床加工得到天线的结构组件。天线的背面是馈电网络,采用了多级的威尔金森(Wilkinson)功分器来保证了天线的宽带特性。天线安装在一个圆形的平台上,平台上单元间设置了隔离板减小了单元的耦合,结合阵列周围的金属挡板有效的提高了天线在低频段的辐射增益。天线仿真增益最高为14dBic,轴比带宽(AR3dB)为1.0GHz-2.2GHz。实测,天线的阻抗带宽为1.0GHz-2.0GHz。基本上满足了某款电磁干扰测试系统对于测试天线的需求。最后,论文给出了全文的总结,并对未来的相关研究进行了展望。
[Abstract]:With the rapid development of electronic technology, more and more people demand the radio system. The miniaturization of the structure and the diversification of the function will be the important development trend of the electronic system in the future. As the front-end device of wireless system, antenna design is closely related to the overall performance of the system. In engineering practice, with the difference of the system application environment, the antenna design must be optimized according to the targets and requirements, so as to give full play to the performance of the system. Aiming at the demand of microwave breast cancer detection system and electromagnetic interference testing system for small wideband antennas, this paper introduces the design and optimization of two wideband directional high gain antennas. It consists of a dipole antenna composed of a multilayer patch and an array of 2 脳 2 element circularly polarized electromagnetic dipole antennas. Firstly, according to the application requirement of the microwave breast cancer detection system, a small high gain directional antenna composed of multi-layer patch is designed and applied to the sensor of the detection system. The antenna is composed of three layers of dielectric plate, wherein, the first layer is a circular metal patch, which is connected with the excitation patch of the middle layer through a metal post; The exciting patch is a circular monopole, and the bandwidth of the antenna is expanded by adding fractal structure to the monopole patch. The third layer is a ring parasitic patch. On the one hand, the parasitic patch can improve the forward gain of the antenna, on the other hand, it can increase the resonance point of the antenna and expand the bandwidth of the antenna. The overall size of the antenna is 38 脳 13.5mmm2, the bandwidth (S11-10dB) of the measured antenna is 3GHz-4.7 GHz, and the maximum gain within the bandwidth is 8dBi. The antenna is applied to the microwave breast cancer detection system. A large number of simulations and experiments on finding the location of the focus are carried out by using the approximate model. Finally, the effectiveness of the antenna design is verified. Secondly, a 2 脳 2 element circularly polarized wideband electromagnetic dipole antenna array is designed to meet the requirement of electromagnetic interference measurement system. The unit adopts electromagnetic dipole structure, and the antenna structure component is obtained by high precision NC machine tool. A multistage Wilkinson (Wilkinson) power divider is used to guarantee the wideband characteristics of the antenna. The antenna is mounted on a circular platform on which the isolation plate is arranged between the elements to reduce the coupling of the elements and the metal baffle around the array can effectively improve the radiation gain of the antenna in the low frequency range. The maximum gain of antenna simulation is 14dBicand the axial ratio bandwidth (AR3dB) is 1.0GHz-2.2 GHz. The measured impedance bandwidth of the antenna is 1.0 GHz to 2.0 GHz. It basically meets the requirements of a certain electromagnetic interference testing system for testing antenna. Finally, the paper gives a summary of the full text and prospects for future research.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN822

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