超宽带谐振腔测试复介电常数的技术研究

发布时间：2018-02-05 20:09

本文关键词： 同轴腔圆柱腔一腔多模模式净化复介电常数　出处：《电子科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：为了实现在0.5-40GHz频段内,对固体介质的复介电常数进行测量。本文将0.5-40GHz拆分为三个频段一个同轴谐振腔覆盖0.5-5GHz频段、两个圆柱腔分别覆盖7-18GHz和18-40GHz。三个腔体都采用了一腔多模技术。本文主要研究工作如下:1)谐振腔中模式众多,通过分析模式分布选定工作模式。根据测试频点应尽量多,且应均匀分布在频段内的要求。分析计算并绘制了圆柱腔工作模式分布图,最终圆柱腔中采用011TE到017TE七个高次模式、同轴谐振腔中用001TEM到005TEM五个模式为工作模式。2)针对圆柱腔中工作模式为高次模开展了模式净化工作。圆柱谐振腔中工作模式为高次模,附近杂模很多,如不采取相应技术措施,使用时会严重影响测试准确度。通过对腔体尺寸优化,使杂模和工作模式频差达到最大。另一方面分析工作模式和简并模式场分布的不同点。通过增加后腔以及优化耦合馈电位置,来对简并模式进行抑制。抑制后得到的工作模式21S扫频曲线关于谐振频点基本对称。3)基于腔体工作带宽和杂模抑制要求,开展了馈电及耦合装置设计。为了满足两个圆柱腔宽频带耦合馈电,设计了对应频段的双脊波导到同轴线转换器。7-18GHz转换器驻波小于1.2、18-40GHz转换器驻波小于1.4,满足带宽要求。馈电位置要能够激励起所有工作模式,同时不激励或者弱激励起简并模式4)基于模式分布、模式净化和耦合馈电,开展了谐振腔的整体设计。针对传统圆柱腔测试介质时放置介质不方便、测试繁琐的问题。对圆柱谐振腔的开腔方式做了创新改进,通过在腔壁中打通孔加入滑轨,在滑轨顶端加入弹簧。在不影响圆柱腔场分布,不改变原来腔体测试精度情况下,使得空腔测试和加入介质测试,这两种测试方式的切换,变得快速简单。这是本文的创新点。另外同轴腔开路端辐射太大影响测试精度,在开路端采用渐变结构,使开路端直径大大减小,减弱腔体辐射以保证测试精度。对谐振腔进行空腔实测,测试结果和仿真结果基本一致。用18-40GHz圆柱腔测试介质样品,相对介电常数测试结果相对误差小于5%。
[Abstract]:In order to achieve in the 0.5-40GHz band. In this paper, the complex dielectric constant of solid medium is measured. In this paper, 0.5-40GHz is divided into three frequency bands and one coaxial resonator is covered with 0.5-5GHz frequency band. The two cylindrical cavities cover 7-18GHz and 18-40GHz respectively. The three cavities are multimode with one cavity. The main work of this thesis is as follows: 1) there are many modes in the resonator. According to the requirement that the test frequency should be as many as possible and should be uniformly distributed in the frequency band, the working mode distribution diagram of cylindrical cavity is analyzed and calculated. Finally, seven high order modes of 011TE to 017TE are adopted in the cylindrical cavity. In coaxial resonator, the five modes of 001TEM to 005TEM are used as working mode. 2). The mode purification work is carried out for the high order mode in the cylindrical cavity and the high order mode in the cylindrical resonator. There are a lot of impurity moulds nearby. If the corresponding technical measures are not taken, the accuracy of the test will be seriously affected when using, and the cavity size will be optimized by optimizing the size of the cavity. On the other hand, the difference of the field distribution between the working mode and the degenerate mode is analyzed. By adding the back cavity and optimizing the coupling feed position. To suppress degenerate mode. The 21s sweep curve about resonance frequency points is symmetric. 3) based on cavity bandwidth and heterodyne suppression requirements. The design of feed and coupling device is carried out. In order to satisfy the broadband coupling of two cylindrical cavities, the standing wave of the dual-ridge waveguide to coaxial line converter .7-18GHz converter is designed to be less than 1.2. The VSWs of 18-40GHz converters are less than 1.4, which meet the bandwidth requirements. The feed position should be able to excite all operating modes without or without weak excitation and degenerate mode 4) based on mode distribution. Mode purification and coupling feed, the overall design of the resonator is carried out. Aiming at the problem that the traditional cylindrical cavity is not convenient to put the medium in the testing medium, the testing is cumbersome. The opening mode of the cylindrical resonator is innovated and improved. By adding slide rail and spring at the top of the cavity wall, the cavity test and the medium test can be done without affecting the field distribution of the cylindrical cavity and changing the measuring precision of the original cavity. The switching of these two testing methods becomes fast and simple. This is the innovation of this paper. In addition, the radiation of the open end of the coaxial cavity has too much influence on the measurement accuracy, and the open end adopts a gradual structure, which greatly reduces the diameter of the open end. The cavity radiation is weakened to ensure the measurement accuracy. The measured results are in good agreement with the simulation results. The dielectric samples are measured by 18-40GHz cylindrical cavity. The relative error of the relative dielectric constant is less than 5.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN015;TN751.2

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