非理想校准件对S参数测量结果的影响

TRL校准方法是矢量网络分析仪（Vector Network Analyzer,VNA）校准的常用方法之一,它通过对直通件、反射件和传输线3个标准件的测量,经过一系列计算获取各误差项的值。但是在实际测量中,这些校准件并不能在整个频带范围内具有理想的特性,从而在实际测量时会引起被测件S参数的测量不确定度。对于使用日益广泛的多端口VNA而言,测量不确定度的分析比二端口VNA更为复杂,目前对其开展的研究还不够广泛深入。文章以四端口VNA为例,对TRL校准过程中由非理想标准件引起的被测件的S参数测量不确定度进行研究。首先,运用广义节点的思想将四端口VNA的S参数测量不确定度用矩阵形式表示,再运用广义TRL校准方法,求得各误差项及其偏移的值,最终求得灵敏度系数的解析式,它可以对四端口VNA进行S参数测量不确定度的B类评估。     

Oscillation detection technique by using Vector Network Analyzer

A Vector Network Analyzer(VNA) can be used to identify oscillation frequency of a signal source with moderate or low Radio Frequency(RF) power if certain care is taken according to experimental results. Unlike reported in the literature that a resonant peak of measured absolute value of reflection coefficient greater than 1 that corresponds to an oscillation frequency, we report that by observing the magnitude change of one-port reflection coefficient across the entire swept frequency range, a sudden peak or a dip corresponds to an oscillation frequency, this is more accurate than other reports. In addition, using modern VNA as a signal detection method can significantly reduce measurement time and increase measurement accuracy to VNA capability for developing emerging signal generating devices at early stage, especially for planar, large quantity and operating in a wide frequency range.     

系统建模与去嵌在RF IC批量测试中的应用

生产测试中通常使用网络分析仪进行射频集成电路(RF IC)S参数测量。一些表贴封装元器件不能直接与网络分析仪连接,通常使用含夹具的测试系统进行连接测试。在无法提供有效校准件的情况下,提出了利用测试系统建模结合去嵌入的方法,解决了RF IC批量测试中的S参数测试问题,并进行了对比验证。     

Microwave diversity imaging using six-port reflectometer

A microwave diversity imaging system conventionally uses a vector network analyzer (VNA) to directly measure the object scattered field (amplitude and phase) over a selected frequency range and viewing angles, then reconstructs the scattering object characteristic function through two dimensional Fourier inversion. In this paper, we present a cost-effective microwave diversity imaging system using a six-port reflectometer, which measures four amplitude (or power) values to acquire the object scattered field indirectly. One can then eliminate the coherent detectors in a VNA. The calibration procedure for this microwave diversity imaging measurement is also described. Experimental results of three types of scattering objects, a metallic cylinder, four distributed line scatterers, and a 72:1 scaled B-52 aircraft model, are presented using the described six-port microwave imaging system     

矢量网络分析仪测量不确定度评估算法

虽然目前校准算法已趋成熟,但由于随机误差和剩余系统误差等的存在,矢量网络分析仪(Vector network analyzer,VNA)的测量结果不可避免地会有一定的不准确性.而现有的矢网测量不确定度评估算法中往往只考虑剩余系统误差,忽略了系统线性性能、线缆状态以及测试环境等因素.本文同时考虑了校准后剩余系统误差、系统非线性误差,随机误差及测量环境等因素,建立了整机测量不确定度模型,实现了矢量网络分析仪整机测量不确定度的评估.与现有矢网不确定度评估算法相比,本算法考虑的误差因素更为全面,评估结果更为可靠.利用误差上限传递思想推导出商用VNA散射参数测量不确定度评估公式,并提供了相应的参数获取方案.应用该算法对安捷伦8753ES矢量网络分析仪进行测量不确定度评估,并与安捷伦提供的技术数据进行对比,其结果数据吻合良好.     

一种基于10项误差模型的二端口矢量网络分析仪校准方法

在三通道二端口矢量网络分析仪(Vector Network Analyzer,VNA)的校准过程中,引入长度未知的50欧姆传输线段作为校准件代替常见的短路-开路-匹配-直通(Short-Open- Load-Thru,SOLT)校准算法中的匹配校准件,减少了校准件数量且不需要已知校准件的全部特性,不仅降低了测试成本,同...     

A new error reduction technique for reflection coefficient measurements for use in quick laboratory tests

ABSTRACT

Reflection coefficient measurement is one of those fundamental methods for determining the performance of radar absorber materials, and reflections due to these measurements are originated from the discontinuities in the measurement system and they result in error. In this paper, a new technique for the calibration of the scalar reflection coefficient measurements in the frequency range of 3–18 GHz in a portable two-sectioned metallic chamber is being proposed for use in quick laboratory tests with reasonable error (redacted error). Calibration measurements are performed by two calibration standards in frequency domain and transformed to time domain for further calculation. Proposed technique exhibits a good agreement with the theoretical values for especially in compact chambers where plane-wave conditions are not fully satisfied, and it is not in need of any complex time gating process. Furthermore, it does not require considering the phase differences which occurs at the measurement plane, providing a cheap and faster solution, reducing time and complexity in characterization of radar absorber materials. This technique with the mentioned test set-up could supply scalar reflection coefficient measurements with overall 0.55 dB error level and useful for practical applications where high level of accuracy is not required.     

机械校准件的量值溯源

本文简单介绍量值溯源的概念,主要阐述用于矢量网络分析仪的机械校准件所需溯源的量值,并给出其溯源图,以确保校准件、矢量网络分析仪以及被测微波件的量值准确性。     

晶圆探针测试系统校准

阐述了消除探针测试系统误差的方法,通过分析校准原理和计算校准模型,提出了把已知的校准位放在校准基片上,通过修改网络分析仪(VNA)的校准位和信号接收端口,利用探针台的移动和探针与校准位的接触提取和反馈信号,修正系统误差。     

Millimeter Wave Measurement of the Low-Loss Dielectric in Vacuum Electronic Devices with Reflection-Type Hemispherical Open Resonator

Accurate dielectric properties are of great importance for the design and fabrication of the input and output windows in vacuum electronic devices. A reflection-type hemispherical open resonator (RTHOR) was designed through theoretical analysis and numerical simulation and also was utilized to measure the dielectric properties of the windows material sapphire. Compared with the two ports measurement, a simplified measurement system to obtain the dielectric performance was proposed and the RTHOR with only one coupling aperture was directly connected to a W-band vector network analyzer (VNA). The material properties can be easily calculated through the VNA measured port reflection coefficient (S₁₁) resonant curve. Investigation shows that the permittivity and the loss tangent of the measured sapphire, which is used to construct the input and output window, is respectively about 9.40 and 1.80?×?10^?4 at room temperature in W-band, which agree well with the reported results. Measured results also show that the simplified measurement system can provide a high accuracy for the measurement of low-loss dielectric in a relatively convenient way.     

Broadband Space Conservative On-Wafer Network Analyzer Calibrations With More Complex Load and Thru Models

An improved vector network analyzer (VNA) calibration approach is demonstrated that utilizes planar lumped short-open-load-thru standards and achieves accuracy comparable to thru-reflect-line (TRL) at high frequency, without the commonly occurring errors in TRL at low frequency. The approach relies on complex load and thru models for coplanar waveguide and microstrip standards that are not currently available in typical VNA firmware. It is shown that the RF performance changes due to variations in fabrication of load can be addressed by “calibrating” or adjusting the load model with the measured dc resistance for a particular load. Good results are shown for a wide range of substrates (GaAs, alumina, and FR-4) and frequencies to 110 GHz.     

紧缩场静区幅相性能现场校准系统

针对国内军用及民用各类型天线及目标特性测量常用的紧缩场静区平面波幅相性能现场校准需求,开展了0.3~110 GHz紧缩场现场校准系统的优化设计。研制了微波幅相收发系统、一体化接收探头天线和八自由度、高精确度可移动大型极坐标扫描设备(半径3 m,平面度均方根值0.04 mm),完成了大型紧缩场静区性能校准系统的研制。利用某航天单位的紧缩场对系统性能进行了现场试验验证,结果表明,研制的校准系统功能强,指标高,可以满足各类型紧缩场校准需求。     

一种低系统误差的干涉仪相位校正方案

借鉴矢量网络分析仪采用标准校正件的方法,提出了一种简单、方便的干涉仪测向低系统误差相位校正方案,通过引入标准功分器作为校准件,来修正校正源通道支路各通道间的不平衡性,最终能够有效消除校正源支路各通道间的固有相差,从而提高系统测向精度.最后,对实现方法进行了定性分析.     

有源相控阵天线自动测试系统设计

针对现代有源相控阵雷达天线T/R组件测试通路多、测试数据处理量大、测试效率低的特点,设计了一种适用于大规模T/R组件测试的有源相控阵天线自动测试系统。该系统设计通过GPIB接口或以太网对VNA(矢量网络分析仪)进行访问控制与数据采集,充分利用了现代计算机强大的数据处理与分析能力,不仅解决了有源相控阵天线故障诊断与自动校正问题,而且还极大地提高了工作效率,节约了人力成本。实际应用表明:该测试系统工作稳定,使用方便,能够充分满足T/R组件测试需要。     

Some measurement results for frequency-dependent inductance of ICinterconnects on a lossy silicon substrate

Frequency dependent measurements of scattering (S) parameters using a vector network analyzer (VNA) have been performed on IC interconnects on a lossy silicon substrate. The multiline calibration method has been used to perform the de-embedding of the line parameters, from which the line inductance is extracted. A highly accurate closed-form approximation for frequency-dependent impedance per unit length of a lossy silicon substrate for IC interconnects has been used to compare with the measurements performed     

Low-Power Testing of Losses in Millimeter-Wave Transmission Lines for High-Power Applications

We report the measurement of small losses in transmission line (TL) components intended for high-power millimeter-wave applications. Measurements were made using two different low-power techniques: a coherent technique using a vector network analyzer (VNA) and an incoherent technique using a radiometer. The measured loss in a 140 GHz 12.7 mm diameter TL system, consisting of 1.7 m of circular corrugated waveguide and three miter bends, is dominated by the miter bend loss. The measured loss was 0.3?±?0.1 dB per miter bend using a VNA; and 0.22?±?0.1 dB per miter bend using a radiometer. Good agreement between the two measurement techniques implies that both are useful for measuring small losses. To verify the methodology, the VNA technique was employed to measure the extremely small transmission loss in a 170 GHz ITER prototype TL system consisting of three lengths of 1 m, 63.5 mm diameter, circular corrugated waveguide and two miter bends. The measured loss of 0.05?±?0.02 dB per miter bend may be compared with the theoretical loss of 0.027 dB per miter bend. These results suggest that low-power testing of TL losses, utilizing a small, simple TL system and a VNA, is a reliable method for evaluating performance of low-loss millimeter-wave TL components intended for use in high-power applications.     

矢量网络分析仪十二项误差校正模型理论推导

首先从网络分析仪的测量体系结构入手,分析测量过程中的误差来源与描述方法,给出相应的误差校正方法的理论公式。并实测了宽带、低损耗器件在两种状态下的测试差异。最后,给出误差校正方法的校正结果与分析讨论。     

Reflection coefficient (Schur parameter) representation for convex compact sets in the plane

We obtain a one-to-one relation between the shape and orientation of a convex compact planar set and a complex-valued reflection coefficient (Schur (1917) parameter) sequence, such that (1) the reflection coefficient magnitudes are less than or equal to one, (2) if any reflection coefficient has a magnitude equal to one, then all subsequent reflection coefficients are equal to zero, and (3) the first reflection coefficient is equal to zero. Three additional independent parameters specify the position of the set in the plane, and the size of the set (specifically its circumference). For a finite duration reflection coefficient sequence, if the last nonzero reflection coefficient has a magnitude that is less than one, then the boundary of the set is an infinitely differentiable convex curve. The boundary is a convex polygon if and only if the magnitude of the last reflection coefficient is equal to one; the number of sides of the polygon is equal to the index of the last reflection coefficient. Almost all planar convex compact sets have reflection coefficient sequences of infinite duration. Such sets can be accurately approximated with convex compact sets that are generated from relatively small numbers of reflection coefficients.     

电波暗室吸波墙壁反射电平测试技术

介绍了测试电波暗室墙壁反射电平的两种方法,既电压驻波比法（VSWR）和基于矢量网络分析仪的改进电压驻波比法（AVSWR）,并对这两种方法进行了比较,给出了每种方法的优缺点。     

Broadband WLAN Channel Sounder for IEEE 802.11b

Because of the proliferation of indoor wireless local area network (WLAN) communication systems, portable radio measurement devices are becoming quite advantageous. This paper reports on the development of an advanced portable and compact broadband WLAN IEEE 802.11b channel sounder, which directly exploits the physical layer characteristics of the WLAN system. The measurement system and experimental procedures have been presented with the measurement results. The channel sounder provides very good results compared to a vector network analyzer (VNA). Moreover, the measured and reconstructed cross-correlation functions from the estimated power taps are in excellent agreement with a root mean square error (RMSE) of 3%. Hence, this system has been developed to be used in conjunction with a WLAN modeling system to calibrate indoor empirical and deterministic models.