介质谐振器介电参数频响特性及频率温度系数的测量

本文讨论了微波介质谐振器介电参数频响特性和频率温度系数的测试方法、测试装置和测试系统。用Q值较高的TE0mn模作为测试介电参数的工作模式 ,取不同下标m和n的TE0mn模式进行测量 ,以获得介电参数的频响特性。为克服常规测试方法因耦合方式不当激励起杂模干扰高次TE0mn 模测试的问题 ,提出了新的耦合方式 ,研制了测试装置。同时 ,还研制了结构巧妙的频率温度系数测试装置。实测表明 ,该测试方法、测试装置和测试系统能对介电参数频响特性及频率温度系数进行快速、准确、可靠、无损伤和批量的自动测试。     

介质谐振器材料及其应用

本文简要介绍自1970年以来得到重大发展的微波介质谐振器陶瓷,指出某些基本规律、特性及研究发展动向,也讨论了材料特征电参数间的相互依存关系。最后举例说明介质谐振器在蜂巢式便携电话中的双工器及稳频振荡器方面的应用。     

基于谐振法测试微波介质材料的介电参数

介电常数是介质材料的主要性能参数之一,该文讨论了微波介质的介电参数的理论计算,分析了谐振法的模型,研制了基于谐振法测量微波介质材料介电参数的测量系统.通过对多个样品进行实测,结果表明与参考值比较吻合,评价了该测量系统测量结果不确定度,从而建立了微波频段内微波介质材料介电常数测量平台.     

微波介质陶瓷材料的研究进展

综述了微波介质陶瓷材料的发展现状，特性及影响因素，讨论了提高微波介质材料性能的途径，并对研究最多的三个材料体系：ＢａＯ－ＴｉＯ２体系，ＢａＯ－Ｌｎ２Ｏ３－Ｌｎ２Ｏ３－ＴｉＯ２体，Ａ（Ｂ‘１／３Ｂ’‘２／３）Ｏ３体系分别予以详细介绍，内容包括：配比，性能，应用以及今后的发展方向。     

微波烧结微波介质陶瓷的研究进展

随着通信行业的发展,尤其是5G商用时代的来临,微波介质陶瓷的开发与探索成了近年来的研究热点.目前通常采用常压固相烧结的方式来制备微波介质陶瓷,但烧结温度较高、加热速度慢,且烧结时间过长,不仅会导致资源的损耗,还可能导致晶粒的异常长大.为了降低陶瓷材料的烧结温度,通常会添加烧结助剂,如B2 O3、CuO等,但加入烧结助剂会引入第二相从而影响微波介电性能.作为一种高效的烧结方法,微波烧结技术是在烧结过程中通过微波与材料粒子的相互作用或微波与基本微观结构耦合产生的热量进行加热,不仅能降低烧结温度、缩短烧结时间,还能改善材料的显微组织,因此,近年来微波烧结成为研究者关注的焦点.采用微波烧结制备的微波介质陶瓷在各个领域中都有应用,如Mg2 TiO4陶瓷用于多层电容器和微波谐振器,BaTiO3陶瓷用于多层陶瓷电容器(MLCC)和随机存取存储器(RAM),MgTiO3陶瓷用于微波滤波器、通信天线和微波频率全球定位系统,TiO2陶瓷用于电容器和低温共烧陶瓷基板等.不仅如此,采用微波烧结制备的微波介质陶瓷还表现出优异的化学稳定性和力学性能,如LiAlSiO4基陶瓷、MgO-B2 O3-SiO2基陶瓷等在多层陶瓷基板与微波集成电路中都有广泛的应用.微波烧结技术为制备优异的材料提供了可能,还可用于在各种粉末的制备,实现性能的进一步提升.本文综述了微波烧结制备微波介质陶瓷的研究进展,总结了常规烧结和微波烧结对材料性能的影响,并指出采用微波烧结制备的微波介质陶瓷目前存在的问题与发展趋势.     

低介微波介质陶瓷基板材料研究进展

低介电常数能减小基板与电极之间的交互耦合损耗并提高电信号的传输速率,高品质因数有利于提高器件工作频率的可选择性和简化散热结构设计,近零的谐振频率温度系数有助于提高器件的频率温度稳定特性。特别在工作频率逐渐提高的情况下,介电损耗不断增大,器件发热量迅速增加,材料的热导率成为一个需要重点考虑的因素。由于陶瓷材料的热导率是有机材料的20倍左右,因此,低介电常数微波介质陶瓷成为制备高性能基板的理想材料。此外,基板材料还需具备高强度和优越的表面/界面特性等综合性能。鉴于此,首先评述了介电常数小于15的低介微波介质陶瓷材料体系的研究进展情况,在此基础上,介绍了降低基板材料介电常数的方法和表面致密化措施,最后指出了在高性能低介微波介质陶瓷基板材料研制过程中面临的问题及今后的发展方向。     

碳纳米管电导率的介质谐振器法测量研究

采用介质谐振器法测量碳纳米管在微波频段下的电导率.本文介绍了利用介质谐振器法测量碳纳米管电导率的理论模型和测量装置,给出了利用该装置测得的一系列测量结果,并对其不确定度进行了分析.     

分体圆柱谐振腔法用于金刚石膜微波介电性能测试的研究

针对金刚石膜微波介电损耗低、厚度薄带来的微波介电性能测试难点, 研制了一台分体圆柱谐振腔式微波介电性能测试装置。利用不同直径的蓝宝石单晶样品, 用上述装置对低损耗薄膜类样品微波介电性能的测试能力及样品直径对测试结果的影响进行了实验研究。在此基础上, 使用分体圆柱谐振腔式微波介电性能测试装置对微波等离子体化学气相沉积法和直流电弧等离子体喷射法制备的高品质金刚石膜在Ka波段的微波介电性能进行了测试比较。测试结果表明, 由Raman光谱、紫外-可见光谱等分析证明品质较优的微波等离子体化学气相沉积法制备的金刚石膜具有更高的微波介电性能, 其相对介电常数和微波介电损耗值均低于直流电弧等离子体喷射法制备的金刚石膜。     

行波管夹持杆微波性能的自动测量

本文讨论了行波管夹持杆微波性能的测试技术。采用模式识别技术，实现了在不同频段用一测试腔对夹持杆介电参数的测量。     

Dielectric Resonators for the Measurement of Superconductor Thin Films Surface Impedance in Magnetic Fields at High Microwave Frequencies

We present the design and realization of cylindrical dielectric resonators operating in the 40–60 GHz frequency range, designed for the measurement of the surface resistance and of the surface reactance shift in High-T _c Superconductors (HTS) thin films in a dc magnetic field. The resonators are single tone, based on the TE ₀₁₁ mode, and multiple tone, the latter allowing in principle to exploit the simultaneous determination of the surface impedance at different frequencies. As an application example, we report the temperature and field dependencies of the effective surface impedance of some cuprate superconductors thin films. The results are compared with those obtained through the use of a standard metal cavity with a similar Q-factor and operating in the same frequency range. The comparison highlights a superior stability and a higher sensitivity, resulting in an increase of about two orders of magnitude in the resolution of the surface impedance measurement. By contrast, the dissipative part of the superconducting transition (above T/T _c = 0.97) is better studied with the metal cavity. We also present measurements in the vortex state in YBaCa₂Cu₃O_7−δ and Tl₂Ba₂CaCu₂O_8+x that show significantly different physics. PACS: 74.25 Nf.     

Measurements of the Electromagnetic Properties of Materials with Low UHF Losses by Dielectric Resonator Methods

Two methods for measuring the electromagnetic properties of materials at ultrahigh frequencies based on a dielectric resonator are analyzed. Combination of the methods makes it possible to reduce errors for measurements of material dielectric permittivity and magnetic permeability. Measurement errors are evaluated.     

The Accuracy of Dielectric Measurements in a Cylindrical Cavity H01p Resonator

The error of measurements of the dielectric parameters and tan in a cylindrical cavity resonator supporting the H _01p mode by varying the length of the resonator at a constant resonance frequency is considered. The errors in measuring and tanare investigated numerically as a function of the electric thickness of the sample being investigated and its permittivity .     

BiNbO4微波介质陶瓷的研究

本文研制V2O5和V2O5－CuO复合添加的BiNbO4微波介质陶瓷．实验结果表明：CuO－V2O5复合添加，比单独加入V2O5能大幅度地降低BiNbO4陶瓷的烧结温度，有效地抑制晶粒异常生长，促使瓷体晶粒尺寸较为均匀和致密，降低高频和微波频率的tanδ值．CuO-V2O5复合添加BiNbO4介质陶瓷，在3GHz频率下，εr＝44；Q＝2000     

Measurements of the Dielectric Parameters of Weakly Absorbing Liquids in the Microwave Band

A method of measuring the dielectric properties of weakly absorbing liquids in the microwave band is proposed. The method is based on analyzing the standing-wave field for thicknesses of the liquid layers for which the conditions for total nonreflecting absorption of the incident radiation to occur in the layer of material, or conditions close to this, are satisfied.     

The Metal-Dielectric Resonator Method of Measuring the Parameters of Radio Materials

The use of symmetrical H- and E-modes and asymmetrical E-modes in a longitudinally anisotropic dielectric cylinder with metal mirrors at the ends to measure its permittivity and dielectric loss tangent is considered. It is shown that the method has wider possibilities compared with the IEC-61338 recommendations. The results of a measurement of the dielectric parameters of a number of materials in the 2–78 GHz frequency band, including the permittivity tensor of sapphire, are presented. __________ Translated from Izmeritel'naya Tekhnika, No. 9, pp. 65–70, September, 2005.