【作者】 郑燕；

【导师】 张文超； 秦会斌； 董胜奎；

【作者基本信息】 杭州电子科技大学 ， 电路与系统， 2009， 硕士

【摘要】 作为一种环行传输微波信号的器件,微波环行器广泛应用手机、移动基站、相控阵雷达等各种民用与军用设备中。随着单片微波集成电路的快速发展,研制体积更小,重量更轻的小型化环行器是环行器发展的必然趋势。微带线具有体积小、结构简单、生产成本低、生产周期短等特点,广泛应用于混合微波集成电路和单片微波集成电路中。环行器用铁氧体的薄膜化能够减小环行器的体积,但如何保持薄膜环行器良好的微波特性成为一个难题。基于以上两点,本文设计一种基于微带线的铁氧体薄膜环行器。本文主要完成以下几部分工作。(1)依据铁氧体旋磁材料的特性设计了由横向磁化场作用下的微带铁氧体薄膜环行器。其基板为在400μm钆镓石榴石沉积10μm的钇铁石榴石薄膜。(2)通过对铁氧体旋磁材料的特性分析,确定了器件材料的几何性能参数,以及在研究电磁波在铁氧体介质中的传播特性的基础上,获得其传输波动方程,推算出求解铁氧体薄膜中谐振条件,结合材料参数理论计算出实现10μm条件下的铁氧体薄膜环行器各结构的尺寸。(3)讨论了铁氧体薄膜环行器的基本工作机理,铁氧体薄膜环行结和50欧姆微带线实现了良好的阻抗匹配。同时分析了基板为10μm铁氧体薄膜和400μm介质的特殊结构条件下,微带的阻抗和400μm的下层基板介电常数的关系。(4)在HFSS中对基板相对介电常数,铁氧体薄膜厚度以及铁氧体薄膜的饱和磁矩对微带铁氧体薄膜环行器的性能的影响进行了分析。得出了铁氧体薄膜环行器的中心频率随基板介电常数的升高而向低频率点移动,其性能随铁氧体薄膜的厚度的增大而变好的结论。同时给出了铁氧体薄膜饱和磁矩的设计原则。最后论文给出了在X波段微带铁氧体薄膜环行器的性能仿真曲线,该环行器在8.14GHz实现了良好的微波性能,隔离度大于20dB,插入损耗小于1dB。论文实现了一种微带铁氧体薄膜环行器,在X波段具有插入损耗小、隔离度大的特点。在薄膜环行器设计中得到的结论,可望在微波铁氧体器件的小型化设计中得到应用。更多还原

【Abstract】 Microwave circulator is widely used in mobile phones, mobile base stations, phased array radar and other civilian and military equipment. The mainstream of the circulator is miniaturization and low cost because of the development of monolithic microwave integrated circuits. Microstrip line has many advantages such as small volume,simple structure, low production cost, short production cycle and so on. So microstrip line has been widely used in hybrid microwave integrated circuits and monolithic microwave integrated circuits. Ferrite film can reduce the size of circulator. But how to maintain the perfect microwave characteristics of the ferrite film circulator is a problem. So a ferrite film circulator which is based on microstrip line is designed in this dissertation.The following work is completed in this dissertation: firstly, a microstrip ferrite film circulator controlled by transversely magnetized field is presented. The substrate is using yttrium iron garnet (YIG) film epitaxially grown on gadolinium gallium garnet (GGG).Secondly, the characteristic parameter of device by analyzing the characteristic of ferrite gyromagnetic material is determined. The transmission equation of ferrite is obtained through the study of the EM wave’s propagation characteristic in ferrite. The size of the ferrite used in circulator is designed according to the ferrite characteristic parameter. The characteristic parameter of device by analyzing the characteristic of ferrite gyromagnetic material is determined. Thirdly, the basic working principle of the ferrite thin-film circulator is discussed .and a good impedance matching is achieved between ferrite thin-film ring and 50 ohm microstrip line. The relationship between the microstrip impedance and the substrate dielectric constant with the special structure .The fourth, the performance of the circulator is analyzed with the impact of the relative dielectric constant of the substrate, ferrite thin-film thickness and the saturation magnetic etc. It also achieved the principle of Saturation magnetic moment of ferrite film .In the end, the performance of the microstrip ferrite film circulator in the X-band is given. The result indicates that the circulator in the 8.14GHz has a good microwave performance with isolation is greater than 20dB and insertion loss is less than 1dB.A microstrip ferrite film circulator is designed in this dissertation. Conclusions achieved in this paper can be used in the research of the design of microwave devices.更多还原