一种使用矢量网络分析仪的阻抗测量改进方法

基于反射法理论提出了一种使用矢量网络分析仪测量集总参数元件阻抗的方法,引入阻抗匹配电路,拓宽了矢量网络分析仪的阻抗测量范围.通过对匹配电路二端口网络模型中参量A的分析,给出相应的被测元件的阻抗计算式,消除了夹具对测量结果的影响.采用矢量网络分析仪直接测量法和该阻抗测量法分别测量了5种不同阻值的金属膜电阻,结果表明,该阻抗测量方法的测量精度高于矢量网络分析仪直接测量的精度,可在30 kHz～100 MHz频率范围内实现几欧至千欧阻抗的精确测量.     

网络分析仪在变频器件测量中的应用

网络分析仪为测量变频器件提供了快速而准确的测量方法，根据标量网络分析仪和矢量网络分析仪的测量原理，详细介绍了用标网测量变频器变频损耗的方法，以及用矢网测量变频损耗和相位的方法。分析了两种仪器在测量中的适用范围和优缺点在变频器测量中的优缺点。以正交混频器为例，提供了测量其幅度不平衡和相位不平衡的网络分析仪测量方法；以本振与射频信号频率范围重合的特殊应用为例，介绍了简单准确的测量方法。     

群时延测量的约束条件

本文就使用矢量网络分析仪测量群时延的结果异常,进行了理论分析,明确了测量结果异常的原因。基于此,推导得出了群时延测量的“相位模糊频段”和约束条件,约束条件以不等式的形式给出,包括对矢量网络分析仪扫频带宽（ SAPN）和频率孔径的约束,基于此给出了改善测量结果的技术建议。使用矢量网络分析仪测量传输通道如信道模拟器、延时线等的群时延参量时,该约束条件尤为适用。     

网络的群延特性测量方法介绍

本文从群延迟的定义、测量方法、注意事项及群延迟特性的一次及二次系数的计算等方面介绍群延迟的测量，主要介绍怎样用ＨＰ８５１０Ｃ矢量网络分析仪测量网络的群延迟特性     

微波功率放大器的性能以及增益的测量

介绍一种微波功率放大器增益的测量方法。经校准件进行TRL校准,校准后分别对所用的两只定向耦合器进行耦合衰减、方向性系数、主线插损和输入口驻波比的频率反应进行测量,同时对终端负载的输入驻波比进行测量。最后由安捷伦矢量网络分析仪组建网络参数测试系统对微波功率放大器的增益进行测量。     

网络的群延迟特性测量方法介绍

本文从理论延迟的定义，测量方法，注意事项及群延迟特性的一次及二次系数的计算等方面介绍群延迟的测量，主要介绍怎样用ＨＰ８５１０Ｃ矢量网络分析仪测量网络的群延迟特性。     

矢量网络分析仪校准项目探讨

矢量网络分析仪是一种公认的高性能智能化测量仪器,然而矢量网络分析仪的计量项目却较为繁杂。通过对矢量网络分析仪工作原理及实际应用的分析,探讨了针对不同客户的需求应对哪些项目进行校准,使客户在相应测试领域使用的网络分析仪得到更准确的测量值,为更有效率地开展矢量网络分析仪的计量工作提供了参考。     

微带介质板介质损耗特性的测量

本文着重介绍了如何使用微波矢量网络分析仪测量微带介质基片的介质氕 原理，方法和测量线路。最后还给出了实测的损耗参数。本文所给的测量方法正确，精度高，能够满足工程设计的需要，也可以用于介质板生产厂家的产品特性参数测量和检验。     

RFID测试仪调制指数测量方法

介绍了RFID技术在国内的计量现状和RFID系统的工作原理,详细分析了RFID标签产品在不同频段范围内的应用情况,提出了RFID测试仪的主要计量参数,着重介绍了数字调制指数的测量。根据RFID信号的帧结构和数字调制方式的定义,从理论上分析了调制指数的测量方法,提出使用数字实时示波器和矢量信号分析仪两种方法进行调制指数的测量,介绍了测量方法和注意事项,并对两种方法的测量结果进行了测量不确定度评定。结果表明,矢量信号分析仪比数字实时示波器更适用于RFID测试仪调制指数的测量。     

PNA,ZVA系列矢网在多参数计量方面溯源探讨

Agilent公司PNA系列、R/S公司ZVA系列矢量网络分析仪除具有S参数测试功能外,在增益压缩、互调失真、噪声系数、混频测试方面性能出色,基于此的计量溯源目前尚无明确规范。本文基于高性能的矢量网络分析仪在多参数测试方面的应用,探讨了计量领域对矢量网络分析仪各测试能力的溯源方法,针对矢量网络分析仪开展各参数测试,并分析了测量不确定度。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。