Probes for Microwave Near-Field Measurements

To be satisfactory for microwave near-field measurements, a probe must have desirable polarization characteristics, must have an aperture small enough to indicate the field at a point, must deliver sufficient signal voltage to permit accurate measurement, and yet must not seriously distort the fields. The design of a probe may be simplified if the fields to be measured are known to be almost linearly polarized or to consist only of a traveling wave. Comparison of measurements made with various probes has led to the development of a small open-ended waveguide probe which is simple to construct and has given excellent results.     

An Integrated Sensor for Electrochemical Measurements

A method for the fabrication of a completely integrated solid-state electrochemical sensor which combines a minature liquid junction reference electrode with a CMOS ISFET is presented. The reference electrode is fabricated by preferentially etching silicon to form a porous silicon frit. The CMOS process provides electrical encapsulation of the ISFET. The performance of the reference electrode and CMOS ISFET as an integrated sensor is demonstrated.     

An Empirical Relationship for Electromagnetic Energy Absorption in Man for Near-Field Exposure Conditions

An empircal relationship is presented for the whole-body-average electromagnetic energy absorption in a 180-cell block model of man for near-field exposure conditions. Consideration is restricted to near fields with P polarization (no component of E directed arm-to-arm) in which the magnitude of the incident electric field is maximum immediately in front of the abdominal region. A highlight of this work is the considerably reduced whole-body average energy absorption for near-field partial-body exposures as compared to that obtained under plane-wave irradiation conditions.     

空间电磁环境监测用双探针式星载电场探测仪

针对空间电磁环境监测需求,该文介绍了双探针式在轨电场探测方法.概述了双探针式、天线式和电子漂移式3种检测方法的异同,重点探讨了双探针式电场测量方法的原理、系统组成及测试标定方法.设计实现了敏感探头和数据采集处理单元,通过阻容耦合方式模拟电场仪在轨工作环境对系统进行了测试.测试结果显示SLF,VLF和HF频段的噪声本底分别小于4μVm-1Hz-1/2,1μVm-1Hz-1/2和0.5μVm-1Hz-1/2.     

用于测量工频强电场的集成光学电场传感器

针对工频强电场测量的特点,研究了用于测量高压工频电场的集成光学电场传感器。分析了集成光学电场传感器的工作原理,以及电场传感系统的输入输出性能。设计并实现了工频电场的测量校准装置,对从100V/m到2500V/m的工频电场进行了测量。测量结果表明,这种集成光学电场传感器适合于高压工频电场的测量。     

光纤Michelson干涉仪型折射率和温度同时测量传感器

基于Michelson干涉仪原理,制作了一种可同时测量折射率和温度的全光纤传感器。传感器由单模光纤和一段长度为5mm的细芯光纤错位熔接而成。对该传感器的折射率和温度响应特性进行理论分析,并在折射率和温度的变化范围分别为1.333 3~1.404 9和20~90℃的环境中对传感器的响应特性进行实验研究,结果表明,随着环境折射率的变化,该传感器输出光谱峰值功率的响应灵敏度为-41.10dB/RIU,而光谱峰值波长对折射率变化不敏感;随着环境温度的变化,该传感器输出光谱峰值波长的响应灵敏度为23.15pm/℃,而光谱峰值功率对温度变化不敏感。因此,通过同时监测传感器输出光谱的功率变化和波长漂移量,可实现折射率和温度的同时测量。该传感器制作简单,测量精度高,在生物医学领域有较好的应用前景。     

近场天线测量中采样原则的改进

近场天线测量中，采用大的采样间隔，有利于提高测试和数据处理的效率。本文提出一种改进的采样间隔选取原则，并通过分析采样间隔与无混叠误差方向图角域的关系，说明该采样原则比文献提出的采样原则更合理。     

高精度纳秒强电磁脉冲集成光学电场传感器性能分析

基于铌酸锂(LiNbO₃)结构研制了一种采用马赫-曾德尔干涉仪与领结天线的、可用于纳秒强电磁脉冲测量的高精度电场传感器。通过实验对传感器性能进行了验证,结果表明:该传感器在对纳秒电磁脉冲上升时间、下降时间与脉冲宽度的测量中,最大误差分别仅为3.9%、4.3%与0.3%,测量数据线性度达到0.9991,最小/最大可测电场强度分别达到3kV/m和50kV/m。     

自发自收单站平面近场散射测量的研究

对自发自收单站平面近场散射测量进行了研究,并进行计算机模拟。计算结果表明,利用自发自收单站平面近场散射测量所得的单站RCS相对量在扫描面外法向附近一个角域内具有良好的工程精度。最后,本文指出需要进一步深入研究的几个问题。     

平面近场测量中取样位置误差修正方法的研究

本文提出一种修正近场天线测量中探头集团误差的方法－非线性迭代法。探头的集团误差为可知值,同激光定位系统获得。运用泰载级数展开,可将天线理想波谱表示为误差算子和近场测量数据的形式。通过计算机械模拟,得到迭代修正后精确的近场值。本文在理想值、有误差的值和修正误差后的值之间作了些比较,相应的模拟数据有助于证实此结合。     

An Error Bound for Near-Field Array Synthesis

An expression for the upper bound of any component of the electric or magnetic field at any point in a region is derived in terms of a product of two surface field integrals. The result is most useful for bounding errors in near-field array synthesis, but might have other applications where upper bounds on field magnitudes are desired.     

某传感器的电磁兼容设计

阐述了电磁兼容的基本概念及产品电磁兼容设计的必要性，给出了某传感器的一些电磁兼容设计方法。     

Sensor for Catheter-Based Measurements of Electncal Conductivity

Measurements of the electrical conductivity of blood have found useful application for almost 100 years. Yet the technology of making those measurements has progressed relatively slowly. To facilitate intravascular conductivity measurements we have developed, refined, and validated a microminiature four-terminal conductivity cell which mounts flush with the surface of a catheter and permits continuous calibrated measurement of conductivity. This, together with our previously published model of blood conductivity, permits continuous measurements of indicator concentration as well as monitoring of blood composition. Discussed here is the rationale for this particular sensor design, including issues which are common to any sensor mounted on the surface of a catheter. The sources and forms of noise, drift, and clotting are discussed, as well as the considerations for optimizing performance.     

无相位近场测量和全息诊断中基于泛函极值的相位恢复方法

相位恢复是无相位近场测量和全息诊断的关键技术.本文考虑探头修正,构造加权目标泛函,给出避免局部极值的无相位测量条件.为提高计算效率和工程实用性,对Fletcher-Reeves共轭梯度法采取再开始技术、FFT算法和构造迭代初值等改进措施.数值模拟表明,应利用有关天线和近场测量的先验信息,选取尽量少的搜索变量.实验结果验证了本文方法的正确性和有效性.     

Development of a Wireless Sensor Network with Optical Electric Sensor for Electric Field Measurement

The area of high voltage direct current (HVDC) transmission line is very large, so using cable for electric field monitoring system is very inconvenient. Wireless sensor network (WSN) can solve this problem. Compared with the traditional communication network, WSN has the advantages of small volume, high flexibility, strong self-organization. So it’s more suitable for the construction of distributed electric field monitoring system which has long distance and high mobility. On the other hand, optical E-field sensors are passive devices and they have such advantages as compact structure, wide-band response and wide measuring range which mechanical sensors lack. A distributed wireless system with optical E-field sensor is designed for collecting and monitoring the electric field under HVDC transmission lines. This measurement system has been used in China’s state grid HVDC test base and power transmission projects. Based on the experimental results, this measurement system demonstrates that it can adapt to the complex electromagnetic environment under the transmission lines and can accomplish the accurate, flexible, and stable demands of the electric field measurement.

     

A Decoupled Approach for Near-Field Source Localization Using a Single Acoustic Vector Sensor

This paper considers the problem of three-dimensional (3-D, azimuth, elevation, and range) localization of a single source in the near-field using a single acoustic vector sensor (AVS). The existing multiple signal classification (MUSIC) or maximum likelihood estimation (MLE) methods, which require a 3-D search over the location parameter space, are computationally very expensive. A computationally simple method previously developed by Wu and Wong (IEEE Trans. Aerosp. Electron. Syst. 48(1):159–169, 2012), which we refer to as Eigen-value decomposition and Received Signal strength Indicator-based method (Eigen-RSSI), was able to estimate 3-D location parameters of a single source efficiently. However, it can only be applied to an extended AVS which consists of a pressure sensor separated from the velocity sensors by a certain distance. In this paper, we propose a uni-AVS MUSIC (U-MUSIC) approach for 3-D location parameter estimation based on a compact AVS structure. We decouple the 3-D localization problem into step-by-step estimation of azimuth, elevation, and range and derive closed-form solutions for these parameter estimates by which a complex 3-D search for the parameters can be avoided. We show that the proposed approach outperforms the existing Eigen-RSSI method when the sensor system is required to be mounted in a confined space.     

用于瞬态电磁场测量的宽带脉冲天线

脉冲天线是脉冲雷达、瞬态电磁场测量等应用的关键设备之一。本文描述了用于瞬态电磁场测量的一种宽带脉冲天线的设计，给出了测量结果，测量结果表明，该天线具有高保真和宽频带特性，有有效地发射或接收毫微秒脉冲信号。实际制作的天线已成功地应用于外场瞬态电磁测试系统。     

时域近场测量的间接频域算法和直接时域算法研究

时域近远场变换是时域近场天线测量的关键技术。本文对时域近远场变换的间接频域算法和直接时域算法进行了数值模拟和分析。针对开口矩形波导天线的时域近场测量 ,选取时空采样参数和内插公式 ,用两种算法计算时域远场方向图 ,分析周期性、时域混叠问题和扫描面截断效应 ,在相互比较和验证的基础上 ,指出两者的优、缺点及适用的情况。     

Near-Field and Far-Field Analyses of Alternating Impedance Electromagnetic Bandgap (AI-EBG) Structure for Mixed-Signal Applications

This paper presents near-field (NF) and far-field (FF) analysis of alternating impedance electromagnetic bandgap (AI-EBG) structure in packages and boards. Three test vehicles have been designed and fabricated for NF and FF measurements. Simulation results using a full-wave solver (SONNET) have been compared with measurement results. This paper investigates the radiation due to return current on different reference planes. The analysis results from simulations and measurements provide important guidelines for design of the AI-EBG structure based power distribution network for noise isolation and suppression in mixed-signal systems