A Model for Currents and Voltages Induced Within Long Transmission Cables by an Electromagnetic Wave

A model is presented for determining the transient currents and voltages induced within a long coaxial cable by a uniform plane traveling wave whose variation with time may be specified. The cable may be located above or within a half-space lossy dielectric with the wave incident from the half-space lossless dielectric. This results in a model for either aerial or buried cables with the source of the wave located in the atmosphere. A method is also presented for generalizing the approach to more complex cables encountered in communication systems. A demonstration of the applicability of this model is presented by analyzing the response of a 0.375-in coaxial cable for both aerial and buried situations. An incident electromagnetic wave with a rectangular time domain waveform is used to demonstrate the transient response. This waveshape is adequate to clearly indicate the transient phenomena. It is found that voltage enhancement results in both aerial and buried cables when the incident wave approaches grazing incidence. This voltage enhancement can be significant especially for aerial cables. Cable shield current enhancement also results for an aerial but not for a buried cable.     

An Experimental Investigation of the Distribution of Current And Charge Induced on a Tubular Conducting Cylinder by an Electromagnetic Pulse

The distribution of current and charge induced on a tubular cylinder by an electromagnetic pulse (EMP) is investigated experimentally in the Harvard parallel-plate EMP simulator (HES). The pulse shapes of the current and charge induced on the surface of the cylinder are measured. After Fourier transforms of the observed pulse shapes are taken, the distributions of the several frequency components on the surface are obtained. The measured distribution of each frequency component is then compared with the theoretical distribution calculated using Kao's method.     

Potentials Produced by Arbitrary Current Sources in an Infinite-and Finite-Length Circular Conducting Cylinder

In electrophysiology, the analytical expression of the potentials at the outer surface of a cylinder, caused by an embedded current source distribution, is useful in studies where measured potentials have to be related to unknown generators. The solutions found in the literature for different types of current sources are unfortunately contradictory. This paper rederives the solution to the general case of an arbitrary monopolar or dipolar current source and discloses where and how an error arose in earlier work. The problems encountered during the numerical implementation of the new equations are extensively discussed.     

Currents Induced by a Plane Wave on an Infinite Wire above a Flat Earth

A general formula for the currents induced in an infinitely long perfectly conducting wire above a finitely conducting ground plane is derived. The effects produced by multiple scattering from e the ground are discussed and are shown to be significant.     

Computation of the Impedance of an Infinitely Long Helical Transmission Line by Numerical Methods (Short Papers)

A numerical method is given for the determination of the impedance of an infinitely long thin-wire helix. The propagation constant of the current for zero tangential electric field is found and used in a variational expression for impedance. Asymptotic values of resistance versus pitch are compared with resistances of infinitely long straight-wire antennas.     

On a Class of Electromagnetic Wave Functions for Propagation Along the Circular Gyrotropic Waveguide

The properties of confluent hypergeometric functions as exact electromagnetic wave fnnctions for propagation in a circular waveguide containing azimuthally magnetized remanent ferrite are investigated. Two different forms of solutions of the propagation problem for angular symmetric transverse electric modes are constructed-one in terms of Kummer and Tricomi confluent hypergeometric functions of complex parameter and variable and a second in terms of Whittaker functions. An evaluation of this class of wave functions is performed to sufficient extent, followed by tabulation of their imaginary zeros, providing computation of eigenvalue spectrum and phase characteristics of the gyrotropic guide.     

A General Spectral-Domain Formulation of the Electromagnetic Scattering by a Perfectly Conducting Circular Cylinder

A full-wave method for the two-dimensional scattering problem by a perfectly conducting circular cylinder is presented, providing an exact solution for the Helmholtz equation in very general cases. The method is based on the Fourier series expression of the boundary conditions (Dirichlet and Neumann) generated by an arbitrary, finite-power, incident beam, and the analysis is performed in the complex plane of the analytic continuation of a space spectral variable. This approach allows us to define an analytic continuation for cylindrical wave expansions, working with lossy propagation media and with a full incident spectrum, including inhomogeneous waves, both in E and in H polarization. Convergence of the modal expansion is investigated, to verify that very weak hypotheses are needed, and no geometrical or paraxial approximation is required. Extact expressions for the expansion coefficients are given, in terms of complex intergrations involving the Fourier spectrum of the incident beam.     

Comments on "Potentials Produced by Arbitrary Current Sources in an Infinite-and Finite-Length Circular Conducting Cylinder"

Recently in this TRANSACTIONS, a paper was published1, dealing with the electric potential problem in a circular conducting cylinder. The authors criticize the approach to the same problem as proposed by Okada in 1956. Obviously, an important motive for preparing the paper was the existence of contradictory results from different solution methods found in literature. We want to rehabilitate Okada's paper. We will point to the small error in Okada's paper. Correction of this error removes the confusing difference with other methods.     

电磁脉冲斜入射时无限长近地细导线表面电流的计算

本文应用时域有限差分（FDTD）方法研究电磁脉冲斜入射下无限长细导线的表面感应电流,并考虑了有耗地面的影响,该问题可以转换为二维问题来计算,从而大大节约计算资源,文中给出了各种情况下的感应电流计算结果。     

Application of the Pattern Equation Method to the Analysis of Electromagnetic Wave Scattering by a Thin Cylinder of an Arbitrary Cross Section

An approximate approach based on application of the pattern equation method is developed for solution of the problem of scattering by a thin cylinder. Explicit formulas for integral scattering characteristics that are applicable to cylindrical scatterers of a complex shape are derived. The accuracy of these formulas is controlled by checking fulfillment of the “optical theorem.”     

高空核电磁脉冲照射下车辆表面感应电流研究

高空核电磁脉冲(HEMP)照射下车辆表面感应电流的研究是装甲车辆电磁防护工作的组成部分。根据IEC6100发布的高空核电磁脉冲波形标准,文中建立了高空核电磁脉冲照射下车辆表面感应电流仿真电磁模型,并使用基于FDTD算法的CST软件进行仿真。通过改变HEMP照射方向和去除炮管部位,对比研究不同频点的车辆表面感应电流最大值和峰值区域的变化情况。实验结果表明,不同角度的车辆表面感应电流最大值与照射方向车辆表面结构的复杂度呈正相关变化,在炮管部位有远高于其它部位的感应电流。文中车辆最大感应电流参考值为1.82×103 A/m,重点防护频段为0~40 MHz。     

Excitation of an Enclosed Lossy Cylinder by an Aperture Source (Short Paper)

We present a formulation for an aperture-excited cylindrical structure of circular cross section and of finite length. The solution method is straightforward but it is sufficiently general to permit quantitative estimates of the internal heating. When the axial dependency of the fields is ignored, the solution reduces to one employed earlier in confection with hyperthermic heating of human torsos and limbs.     

分析无限平面金属栅电磁散射问题的一种新方法

本文基于直线法和Floquet定理提出了一种分析无限平面金属栅周期结构电磁散射问题的新方法。数值结果与谱域法结果和实验结果一致,但本文方法具有数学模型简单,计算量小等优点。     

On the Definitions of Parameters in Ferrite-Electromagnetic Wave Interactions (Letters)

Conflicting definitions of the parameters characterizing the material in ferrite-electromagnetic wave interactions occur in the current literature, as well as do actual sign errors that are difiicult to detect because of the variety of signs appended to the relevant quantities by different authors. A harmonious set of definitions are set out and their consistency illustrated using the case of a uniform circularly polarized plane wave.