软件无线电在矢量反射系数测量中的应用

为实现低成本测量,采用LimeSDR 软件无线电模块、定向耦合器和GNU Radio Compainon 软件联合搭建出矢量反射系数(微波S 参数之一)最简测量系统。为验证该测量系统的准确性,先用该系统测量3 个已知的校准件(开路、短路、负载),并结合这3 个校准件采用精确矢量网络分析仪测量得到的准确数据,计算出该测量系统微波网络的误差参数,用于对被测件测量结果的误差修正,从而获得被测件实际的矢量反射系数。与用矢量网络分析仪测量同一被测件的实验结果对比,表明所搭建的测量系统具有较高的测量精度,且同时具有成本低、配置灵活、可扩展性强的特点。     

自动源调配器测量晶体管噪声参数的补偿计算

在微波噪声参数测量系统中,通过使用自动源调配器来改变源反射系数的方法,可以方便地求出各个参数。根据对所引入的自动源调配器的分析,总结出源调配器自身的额外噪声误差是可以忽略的,并在对自动源调配器与噪声源级联后组成的单端口网络进行误差分析后,做出了超噪比的补偿运算,这种误差修正方法在很大程度上减小了测量误差量级。使用该补偿方法可以在噪声参数测量时进行更大范围的源阻抗调配,并提高噪声测量的准确度。     

发射测量用耦合去耦网络的校准方法

发射测量用耦合去耦网络(CDNE)法测量骚扰电压是CISPR认可的最新方法,比传统的辐射发射测量方法具有更小的不确定度和更好的测量重复性。文章介绍了典型CDNE的结构、原理及校准布置,详细阐述了共/差摸阻抗、去耦衰减等计量参数的校准方法,并基于实验室对送检CDNE的校准实践,着重研究了校准方法中的难点——测量共模阻抗时的时延修正电长度和纵向转换损耗测量。通过反复实验分析比较了不同校准模式下的测量结果,验证了校准方法的正确性,为进一步提高CDNE法测量传导骚扰电压的准确性提供参考。     

六端口自动网络分析仪

目前,自动网络分析仪已经遍及微波计量领域。通常所说的自动网络分析仪,就是指由复数比值检波器和各种待测接口所组成的测试设备。自动网络分析仪能够测量单端口器件复反射系数(阻抗)和两端口器件的复散射参数。检波器的响应性能则由测试设备的特性及待测器件的特性来确定。计算机尚未普及时,测试设备的设计者竭力避免繁琐的计算和校准,或使计算和校准尽量得到简化。自动网络分析仪的调节很复杂,并且它只提供了使反射和传输信息都消失的幅度响应检波技术。幅度和相位两者的测定,需要数学处理由复数比值检波器所得到的测量结果。在应用微处理机之前,要完成这样的过程是不可能的。自从高速计算的小型电子计算机问世以后,人们便可用它来测量测试设备的校准参数,计算相应的修正因子,并把这些修正因子用于最后所得到的测量结果。     

矢量网络分析仪的校准方法

该文简单介绍矢量网络分析仪的工作原理,重点阐述误差修正原理以及与误差修正相关的校准件、校准方法和如何进行校准质量的评估。     

智能精密数字多用表自动校准技术剖析

概述 智能精密数字多用表软件功能完善,其中央控制单元采用微处理器来控制完成测量、自动校准、自动补偿、计算等功能。在自动校准过程中,对智能数字多用表的每个功能及每一功能的所有量程,经过测量和计算得到的一系列误差修正常数,都存储在RAM中。每次实际测量时,自动提取这些常数进行修正计算,以确保仪器的测量精度,该项技术具有以下特点。●“不揭盖”校准,不影响热平衡,确保精度及稳定度。● 性能显著提高,对标准跟踪工作非常有用。● 便于使用,自动校准过程可通过按键或IEEE-488命     

微波器件噪声参数的测量方法

作为微波低噪声器件研制和应用的一项关键技术,噪声参数的测量工作引起行业的广泛关注。论述了噪声参数测量原理,研究了测量系统校准方法,分析了噪声源的反射系数、噪声温度,阻抗调配器的反射系数、S参数、增益,接收机的反射系数、噪声功率等20余项物理量对噪声参数测量的影响,对比了直接冷源法和简化冷源法在接收机传输增益测量中的优缺点,提出了改进型冷源法。最后给出了噪声参数测量不确定度主要影响量的归类分析,为下一步开展噪声参数不确定度评定工作奠定了基础。     

自动阻抗测量仪工作原理及阻抗测量方法

介绍了一种由微处理器控制的多频自动阻抗测量仪，其能快速、便捷、准确地测量元件的各项参数。主要叙述了该测量仪的内部结构、工作原理，以及阻抗参数的测量方法和实际工作应用。     

测定射频和微波辐射生物效应的高功率双六端口自动网络分析仪

本文介绍一种工作频段为10—100兆赫的高功率(1—1000瓦)自动网络分析仪的设计、校准和性能,这种分析仪是以六端口概念为基础的。测量反射系数Γ的幅度不精确度为0.0001,而相位不精确度为0.005/|Γ|度。相应的系统估值误差为0.001和0.1/|Γ|度。测量功率的不精确度为功率量程(20瓦、200瓦或1000瓦)的0.01％,其系统估值误差为读数的1.25％。     

矢量网络分析仪校准方法研究

文章简单介绍了矢量网络分析仪的工作原理和误差修正原理．研究了矢量网络分析仪的校准方法及其适用范围,并探讨了实际校准过程中需要注意的一些问题。     

基于SU-8胶转子的非接触压电微马达

研制了一种非接触压电微马达，通过阻抗分析仪对定子进行扫频测试，确定其共振频率，并且详细介绍了SU-8胶转子制作的工艺流程。利用转速仪比较不同形状和尺寸的转子在调频和调压下的转速，从而确立压电微马达的最优转子。转子半径为6mm，叶片宽度为6mm的三叶片转子转速最高为3569r／min。转子的启动电压和最高电压分别为8V和24V。     

Scaled model measurement of the embedding impedance of a 660-GHz waveguide SIS mixer with a 3-standard deembedding method

In this paper, the embedding impedance of a 660-GHz superconductor-insulator-superconductor (SIS) mixer is investigated using a 100-times scaled-model with a new 3-standard deembedding technique. The mixer embedding impedance is extracted from the reflection coefficients measured at the waveguide port of the mixer for three different terminations at the SIS junction's feed point. The three standards chosen are open-circuit, short-circuit and resistive load. Measured results are compared with those simulated by a high-frequency structure simulator (HFSS).     

Asymmetric ring-hybrid phase shifters and attenuators

A new structure of asymmetric ring-hybrid phase shifters and attenuators is presented. Each consists of an asymmetric ring hybrid and reflecting terminations, and it does not have any additional 90° phase delay line for utilizing symmetric reflecting terminations that conventional phase shifters use. To analyze these asymmetric ring-hybrid phase shifters, normalized impedance ratios NI_b and NI_d are introduced, and the possibilities to reduce the size of the reflecting terminations are presented. Using the new structure of the asymmetric ring-hybrid phase shifters, asymmetric ring-hybrid attenuators are synthesized. To analyze the attenuators, normalized resistance ratios NR_Lb and NR_Ld are introduced, so that the resistances in the reflection terminations can arbitrarily be determined. On the basis of the derived new structures, a uniplanar asymmetric ring-hybrid -135° phase shifter and a microstrip asymmetric 4-dB attenuator with 45° phase shift have been fabricated and measured. They show good agreement between measured and simulated results and they may be used for impedance transformers besides their original functions     

An Adjustable Sliding Termination for Rectangular Waveguide

A new adjustable sliding termination for rectangular waveguide has been developed. The termination is of simple design and can easily be adjusted to have reflection coefficients from zero to nearly unity in magnitude and any desired phase. In addition to the usual applications of adjustable sliding terminations for rectangular waveguide, it provides a suitable design for an adjustable transferor secondary standard of impedance for rectangular waveguide systems.     

Error-corrected large-signal waveform measurement system combiningnetwork analyzer and sampling oscilloscope capabilities

A large-signal automatic stepped CW waveform measurement system for nonlinear device characterization is presented that combines the high accuracy of a vector network analyzer with the waveform measurement capabilities of a sampling oscilloscope. A large-signal error model and a corresponding coaxial calibration procedure are proposed to describe the systematic errors of the measurement setup. The error parameters and the correction algorithm are independent of the properties of the RF generator. System accuracy is investigated by Schottky diode verification measurements with different offsets from the reference plane. GaAs MESFET reflection and transmission response measurements with error correction extended to the planar device under test (DUT) reference planes are given     

Narrow-band matching networks for quasi-TEM coupled microstriplines

For coupled-line systems, "matching" involves entire impedance matrix networks and necessarily involves multiple propagating modes. This paper presents the synthesis of several matching strategies for symmetric coupled-line microstrip structures mismatched with several types of simple passive terminations. Detailed multiconductor transmission-line analysis provides the basis for procedures to optimize the parameters of several matching networks (stubs, reactances, transformers) that yield significant line and mode reflection reduction resulting from the mismatches. Measurement of synthesized structures verifies the reflection reduction and power savings     

Electromagnetic fields with arbitrary wave impedances generatedinside a TEM cell

It is shown that arbitrary electromagnetic fields and wave impedances can be generated inside a transverse electromagnetic (TEM) cell for RF susceptibility testing. This is achieved by simply exciting one port and terminating the other port with appropriate loads. Thus, TEM cells are not limited to producing a planar field environment with the free-space impedance of 377 Ω, but can also be used to generate high-impedance or low-impedance fields for special testing needs. Experimental results for only three load impedances are described. In principle, many other loads including reactive terminations could be used to create a particularly desired field and wave impedance inside the TEM cell     

Reflection Charts Relating to Impedance Matching

A reflection chart is some grid of coordinates on which to plot an impedance locus over a frequency range. Taking as a reference a constant real impedance, one may construct contours of the reflection coefficient (or the related VSWR, reflection loss, etc.). The reference may be the wave impedance of a transmission line. This may be a line connecting radio equipment with an antenna or it may be a standard line used in measuring the impedance. The reflection chart in widest use is the so-called "Smith Chart" proposed by Philip H. Smith in 1939. It is one form of the hemisphere chart, which was proposed, also in 1939, by Philip S. Carter. Its properties, uses are described. It has some limitations. A reference value must be assigned, after which the shape of a locus depends on this value. Also, a locus is crowded toward the rim of the chart. A logarithmic reflection chart has recently been proposed by the author, which overcomes these limitations but loses some desirable features of the hemisphere chart.     

时域近场测试中的探头误差分析与修正

探头误差分析和修正是时域近场测量中的关键技术.本文详细推导了探头自身接收特性误差函数在修正过程中的坐标变换关系,提出用 '时间窗' 技术隔离掉探头和待测天线之间的多重反射波,并导出'时间窗’的选取原则,数值结果证明了理论和方法的有效性.     

Analog line driver with adaptive impedance matching

A new principle for an adaptive line driver is presented. This type of line driver can adapt its output impedance automatically to the applied load. This results in automatically corrected output impedance for different cables with terminations. Also, the line-driver output impedance becomes insensitive to process variations. As an example, a line driver for analog video signals has been designed. The circuit operates from a 2.4-V supply in a 0.35-μm CMOS technology. The realized circuit adapts between 38 and 85 Ω loads, has total harmonic distortion of <-50 dB at 1.2 V_pp for 0-10 MHz, 0.09-mm² area, and 9-mW static power consumption