Transmission Line Mode Response of a Multiconductor Cable in a Transient Electromagnetic Field

This paper describes a technique for obtaining the induced worst case currents on individual wires of a multiconductor cable as a result of a transient electromagnetic radiation field. The technique involved a development of the expression for the induced current in matrix form where the mutual coupling terms and the other cable currents are the pertinent parameters. A worst case solution results from the assumption of maximum coupling orientation of the individual wires. A short example and some test results are presented. The test results show wave shapes for inductive and capacitive coupling. The solution for the individual wire current due to a transient electromagnetic field is important, since it will greatly reduce the required number of cable measurements and will allow the development of improved shielding techniques.     

Transient Response of Multiconductor Transmission Lines Excited by a Nonuniform Electromagnetic Field

The time-domain transmission-line equations for uniform multiconductor transmission lines in a conductive, homogeneous medium excited by a transient, nonuniform electromagnetic (EM) field, are derived from Maxwell's equations. Depending on how the line voltage is defined, two formulations are possible. One of these formulations is considerably more convenient to apply than the other. The assumptions made in the derivation of the transmission-line equations and the boundary conditions at the terminations are discussed. For numerical calculations, the transmission -line equations are represented by finite-difference techniques, and numerical examples are included.     

Uncertainty Analysis of Dipole Antenna Calibration Above a Ground Plane

A thorough analysis of the uncertainty for dipole antenna calibration is presented. The primary standard of the antenna factor (AF) is obtained by the three-antenna method (TAM), and an ordinary calibration service is performed using the reference-antenna method (RAM). As the AF of the standard antenna is necessary for the RAM, the uncertainty analysis of TAM with the specified antenna setting is presented first, followed by the analysis of RAM. The Guide to the Expression of Uncertainty in Measurement (GUM) shows how to analyze and express the measurement uncertainties. According to the GUM, the uncertainty analysis of the calibration procedure is formulated by expressing AF as a function of other quantities, and every source of uncertainty that affects the result of the measurement is evaluated. An example of the uncertainty budget at 400 MHz is shown, and uncertainties at 24 frequencies in the range of 30 to 1000 MHz for TAM and RAM are summarized. To validate the uncertainty analyses, the differences between the calibrated and calculated AFs are shown to be smaller than the expanded uncertainties with the coverage factor of 2(k=2)     

平面电磁波对双导线传输线终端瞬态响应的求解

随着传输线方法在电磁兼容和电磁干扰分析方面的广泛应用,人们对传输线方程的求解方法也越来越感兴趣.求解传输线方程的方法通常有时域差分方法和频域差分法.而对于平面电磁波对双导线传输线终端的响应,文章给出了其频域解析解,并且运用这个解析解和Fourier变换技术,可以很容易地给出传输线终端的瞬态响应分析.通过数值仿真实验研究三个角度参数φ、α和Ψ在电磁感应中的作用:当φ和α保持不变(或者Ψ和α保持不变),随着Ψ(或者φ)的增大,终端2的感应电流的响应时间缩短,第一阶段的感应时间延长;当φ和Ψ保持不变,随着α的增大,终端2处第一阶段的感应电流也随之减小.     

Comparison of Quasi-Static and Exact Electromagnetic Fields from a Horizontal Electric Dipole Above a Lossy Dielectric Backed by an Imperfect Ground Plane

In most microstrip transmission lines, analysis is made assuming that a quasi-TEM mode exists and propagates down the line. The primary objective of this paper is to obtain the region of validity of this assumption. The second objective of this paper is to derive the expressions for the fields for a horizontal electric dipole over a Iossy dielectric medium backed by an imperfect ground plane. It is shown that, to a first approximation, fields at the air-dielectric interface are independent of the ground plane conductivity. Since we are interested in coupfing between lines, our interest is in the computation of the fields primarily at the air-dielectric interface. Finally, numerical results are presented to show where the quasi-static approximations deviate from the exact solution for a given microstrip geometry as the frequency of operation or the observation point is changed.     

Frequency Response of Multiconductor Transmission Lines Illuminated by an Electromagnetic Field

A well-known result [1], [2] for the response of a two-wire transmission line illuminated by a nonuniform electromagnetic field is extended to multiconductor lines. A simple matrix equation for the currents induced in arbitrary termination networks is obtained. Air Development Center.     

常阻抗地平面上方垂直电偶极源电磁场的精确和有效解

地平面上方偶极源的电磁场可以分解成直达波场、镜像波场和Somm erfeld型积分三部分之和。应用圆柱波函数的球面波展开式和超几何函数理论,常阻抗地平面上方垂直电偶极源电磁场中的Somm erfeld型积分被表达成圆柱波函数(表面波模)与快速、绝对收敛的球面波函数集展开式之和;其级数展开式的系数是以表面阻抗为宗量的勒让德函数。该展开式数学物理意义明显,并且便于计算,它是此类Somm erfeld半空间问题的精确、有效解答。     

Investigation of a Dipole Model for Transient Analysis of Electromagnetic Field Coupling into Long Cables

The authors describe a mathematical model for a long conductor exposed to a high-intensity transient electric field to aid in determining interface requirements at connected equipment. Dipole characteristics of the conductors are used to simulate the impedance and in turn to calculate the induced currents. Example calculations for four models, two conductor lengths, and two conductor sizes, are presented and compared.     

近地对数周期偶极天线的分析

采用矩量法结合离散复镜像法求解近地对数周期偶极天线的电流分布，用基于驻相法的远场Som-merfeld积分近似公式求解辐射场。在计算广义阻抗矩阵元素时，利用矩阵的互易性和天线阵的结构对称性进行了算法优化，从而大大提高了计算速度。     

Waves Guided by Conductive Strips Above a Periodically Perforated Ground Plane

This paper considers the propagation of waves along an array of conductive strips situated above a periodically perforated conductive plane. Each conductor has zero thickness and finite sheet resistance, and the dielectric is homogeneous. The surface current density on the conductors is approximated by a finite number of current elements having rooftop spatial dependence. The transverse electric field is expressed in terms of the current, and the electric field boundary condition is satisfied in an integral sense over the conductors. This generates a matrix equation whose solution gives the dispersion curve relating the propagation constant to frequency, as well as the current distribution. The simulation results are used to obtain equivalent transmission-line parameters applicable to printed circuit boards found in high-performance computers. A characteristic impedance is defined and it is shown that, with proper interpretation, the uniform transmission-line equations for propagation constant and characteristic impedance apply to such computer packages. The coupling between adjacent strips is caculated, and the effect of finite resistivity discussed.     

On the Response of a Terminated Twisted-Wire Cable Excited by a Plane-Wave Electromagnetic Field

The currents induced in the terminations of a twisted-pair cable are obtained for a plane-wave electromagnetic-field. Various termination configurations are considered and comparisons are made with the corresponding results for untwisted pairs. In special cases, the twisted cable may have a larger induced signal than the untwisted. Under various common restrictions, the induced signal is inversely proportional to either 1) the square of the number of turns or 2) the number of turns.     

高速集成电路中多导体传输线的电磁参数提取与瞬态响应分析

本文在直线法中引入了一种新技术，将多层介质多导体结构的各层介质等效为级联的坪端口网络，介质层间导体等效为端口的电流源，从而大大简化了公式推导，方便了编程计算。     

Resonance Properties of the Shield of a Coaxial Cable over a Ground Plane

In situations where several high-power transmitters and their antennas are to be used near one another, a certain amount of mutual interference can be expected. An instance of particular interest is that of high-intensity radiation inducing standing waves between the shields of nearby coaxial cables and a metal deck of ground plane. Standing waves induced may cause high potentials and possible breakdown at the ends of the cable, damaging connectors and antennas. There may also be some reduction of the shielding effectiveness of the coaxial cable when high-voltage standing waves are present in the shield. It has been common practice to eliminate such standing waves by periodic grounding of the outer conductor of the coaxial cable. This, however, requires penetration of the insulation material on the cable and formation of metal-to-metal joints on the shield. This is not only an inconvenient method of installation, but is also undesirable around salt water. Copper shielding will corrode, and corrosion at the joint of the dissimilar metal can cause nonlinear interference effects. The standing waves induced in the transmission system formed by the cylindrical shield of a coaxial cable and a conducting plane are examined theoretically and experimentally as a function of the shield-to-ground impedance at the end points only (Z1 and Z2 of Fig. 1). Ordinarily, standing waves are eliminated by terminating a guiding system in its characteristic impedance. In this situation, however, the exciting source (i.e., incident radiation) is distributed along the length of the transmission system.     

On the Response of a Missile with Exhaust Trail of Tapered Conductivity to a Plane Wave Electromagnetic Field

The current distribution along and scattering cross section of a missile with plume (ionized trail) is found, using numerical techniques when the conductivity of the plume tapers with increasing distance from the exhaust nozzles. In the theory no restrictions are imposed on the length of either the missile or plume, and the variation of conductivity along the entire scattering obstacle may be arbitrary. A model of cylindrical geometry is assumed. Curves for the current distribution along the missile and its ionized trial are presented for several missile and plume lengths at selected frequencies. A table is provided for the scattering cross sections.     

有限导电平面上方电偶极子电磁场的解析公式

利用广义阻抗边界条件来模拟有限导电平面对电磁场的影响。在此边界条件下,推导出有限导电平面上垂直和水平电偶极子电磁场的解析表达式;赫芝位函数中的索末菲型积分被表达成零阶汉克尔函数与绝对收敛的球汉克尔函数级数之和的形式。利用这些解析公式可方便、准确地计算和分析任意取向电偶极子电磁场的分布。     

Properties of the Lateral Electromagnetic Field of a Vertical Dipole and Their Applications

The Formullas For The Electromagnetic Field In Region 1 (Z ? 0, K1) Due To A Vertical Electric Dipole Also In Region 1 Near Its Plane Boundary With Region 2 (Z ? 0, K2; |K2|2 << |K1|2) Are Reviewed. The Corresponding Formulas For The Field In Region 2 Are Then Determined. Use Is Made Of This Field To Determine The Locus Of The Poynting Vector And The Maximum Depth Of Penetration Into Region 2 Of The Lateral-Wave Part Of The Field. Application Is Made To The Use Of The Vertical Antenna In The Sea For The Measurement Of The Conductivity Of The Oceanic Crust.     

双极天线的核电磁脉冲响应特性研究*

针对应用较为广泛的一种短波双极天线,利用CST 仿真分析了天线对高空核电磁脉冲(HEMP)的响应特性。计算了双极天线分别在自由空间和导体板上方时的天线端口开路及端接50 赘负载情况下的响应特性,得出了天线在两种情况下端口的感应电压时域和频域信号及负载的沉积能量,并探讨了其随电磁脉冲入射角兹、导体板半径R 和天线高度H 的变化规律。仿真结果对于实验方案的制定及天线系统防护具有重要指导意义。     

Electromagnetic Field Analysis for a Coaxial Cable with Periodic Slots

The analysis deals with the excitation of coaxial structures with periodic apertures in the outer cylindrical shield. These apertures are taken to be finite circumferential slots of thin width. A quasistatic method is employed that reduces the problem to a field matching of angular wave functions over the angular extent of the slots. An approximate averaging technique is then used to obtain expressions for the effective admittance of the cable. It is then argued that this can be used to characterize the cable in more complicated environments.     

基于时域有限差分法的电缆系统电磁瞬态分析

深入研究电缆系统的电磁瞬态过程对于合理解决高压电缆系统的过电压防护、绝缘配合和电磁干扰等工程问题具有极为重要的实际意义.传统的计算方法如电力系统电磁瞬态计算程序EMTP软件需同时考虑电缆分布参数和相模变换矩阵的频变特性,过程较为繁琐.基于时域有限差分算法,提出了一种新的电力电缆电磁瞬态分析的计算模型.该模型仅需在相域考虑电缆阻抗参数的频变特性,既保证了计算精度,又简化了计算过程.通过与其它电缆计算模型相比较,验证了算法的正确性.最后,将所提算法扩展应用于同轴电缆系统的瞬态分析,计算结果与实验结果相当吻合.