Extension of quasi-static range finitely conducting Earth-image theory techniques to other ranges

By a simple extension to the Wait and Spies quasi-static range image theory approximation, it is shown that finitely conducting earth-image theory techniques can also be extended to the near-field and far-field ranges.     

Image Theory Results for the Mutual Impedance of Crossing Earth Return Circuits

Suitable engineering expressions for the mutual impedance of crossing earth return circuits are derived by employing finitely conducting earth image theory techniques. It is shown that the image theory and previously derived analytical results, which are rather complicated, are in excellent agreement.     

Summary of image theory expressions for the quasi-static fields of antennas at or above the earth's surface

Expressions for the quasi-static range (the measurement distance is much less than a free-space wavelength) field components produced by infinitesimal dipole antennas located at or above that of the earth have been derived by employing finitely conducting earth theory techniques. Formulas for the field components produced by an elevated, finite-length, horizontal electric antenna are also presented. Image theory is employed because most of the resulting integrals encountered cannot be evaluated analytically. The image theory and previously derived analytical (or in some cases, numerical integration) results are in agreement throughout the quasi-static range.     

Analysis of Thick Rectangular Waveguide Windows with Finite Conductivity

The modal analysis method is used to calculate the reflection and transmission properties of a thick rectangular window centrally located in a rectangular waveguide. Excellent agreement is obtained between calculated and measured values for windows of intermediate thickness. For thicker windows made of finitely conducting materials, the results obtained using perfectly conducting waveguide modes are inaccurate. However, by modifying the modes so as to include some of the mode-coupling effects caused by the surface currents, good agreement between calculated and measured data is obtained for a very thick, finitely conducting window.     

An Approximate Time-Domain Formula for the Calculation of the Horizontal Electric Field from Lightning

This paper presents an approximate formula to calculate the horizontal electric field from lightning, considering finitely conducting earth. The formula is represented by an analytical expression in the time domain, which is useful for the calculation of lightning-induced voltages on power and telecommunication lines, without the need of domain transformations. The paper also compares the results of the formula with the results obtained from frequency-domain techniques, namely the numerical calculation of Sommerfeld's integrals and the Cooray-Rubinstein's formula. The comparison is favorable for a wide range of distances from the lightning channel and values of earth's conductivity. The horizontal electric field calculated by the formula is composed of two components of opposed polarities, one due to the return stroke charge and the other due to the return stroke current, resulting in an electric field with a bipolar wave shape. The charge component prevails in the region close to the lightning channel, while the current component prevails in the region far from it.     

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.     

分层介质中平面电磁波的传播与Zenneck波

平面电磁波作为一种理想的电磁波型,其在均匀介质中的传播特性分析是电磁场理论基础教学的核心内容.特别是均匀平面波由理想介质入射到与导电媒质平面分界面时的传播规律,是地球物理勘探、陆地移动通信工程及光纤传输技术的理论基础.本文分别以理想介质与理想介质和导电介质构成的两层平面分层媒质为例,应用场匹配方法,给出反射波和传输波分析求解的统一描述.与传统的处理方法相比,具有数学分析简洁严密与物理概念准确清晰的特点.     

Lightning-induced voltages on overhead lines

A modeling procedure that permits calculation of lightning-induced voltages on overhead lines starting from the channel-base current is discussed. The procedure makes use of a coupling model already presented in the literature, based on transmission line theory, for field-to-overhead line coupling calculations. Both models are discussed and compared with experimental results. The hypothesis of perfect conducting ground, used to analyze the voltages induced on an overhead line by a nearby lightning return stroke with a striking point equidistant from the line terminations, and the limits of its validity are determined. A comparison shows that peak value and maximum front steepness of the induced voltages calculated using other lightning return-stroke models differ. It is also shown that another coupling model used in the power-lightning literature by several other authors may result in a less accurate estimation of the induced voltages     

The effect of secondary scattering on the induced current in a longwire over an imperfect ground from an incident EMP

The effect of secondary scattering that is produced by the induced current in an infinitely long, finitely conducting wire over a plane, finitely conducting earth from an incident electromagnetic pulse is investigated. This is accomplished by finding the field of a Hertzian dipole over the earth and identifying the part that is due to secondary scattering. Frequency-domain results for the overall induced current require that certain infinite integrals be numerically evaluated. Fourier inversion to the time domain in turn requires the numerical evaluation of another infinite integral. When the results are compared to those obtained when secondary scattering is ignored, it is found that secondary scattering slightly increases the current for the case of broadside incidence and reduces it for the case of grazing incidence by as much as two orders of magnitude. Peak currents are much smaller than previously thought. These general results hold for all of the earth parameters that were used in the study     

Sommerfeld and Zenneck wave propagation for a finitely conductingone-dimensional rough surface

Starting with Zenneck and Sommerfeld wave propagation over a flat finitely conducting surface has been extensively studied by Wait (see IEEE Antennas Propagat. Mag., vol.40, p.7-24, 1998) and many other authors. We examine propagation over a finitely conducting rough surface, also studied by many people including Feinberg (1944), Bass and Fuks (1979), and Barrick (see Radio Sci., vol.6, p.517-26, and vol.6., p.527-33). This paper extends the multiple scattering theories based on Dyson and Bethe-Salpeter equations and their smoothing approximations. The theory developed here applies to rough surfaces with small root-mean-square (RMS) heights (σ<0.1λ). We limit ourselves to the one-dimensional (1-D) rough surface with finite conductivity excited by a magnetic line source, which is equivalent to the Sommerfeld dipole problem in two dimensions (x-z plane). With the presence of finite roughness, the total field decomposes into the coherent field and the incoherent field. The coherent (average) field is obtained by using Dyson's equation, a fundamental integral equation based on the modified perturbation method. Once the coherent field has been obtained, we determine the Sommerfeld pole, the effective surface impedance, and the Zenneck wave for rough surfaces of small RMS heights. The coherent field is written in terms of the Fourier transform, which is equivalent to the Sommerfeld integral. Numerical examples of the attenuation function are compared to Monte Carlo simulations and are shown to contrast the flat and rough surface cases. Next, we obtain the general expression for the incoherent mutual coherence functions and scattering cross section for rough conducting surfaces     

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。     

A heuristic UTD slope diffraction coefficient for rough lossywedges

Heuristic wedge diffraction coefficients for computing propagation path loss over finitely conducting earth are extended to include slope diffraction, with the assumption that propagation of energy through the wedge is negligible. The slope diffraction terms for the lossy wedge are obtained in an analogous manner as for the perfectly conducting case, except that special care must be taken with the factor multiplying the incident field for grazing incidence. Results given show that the slope diffraction term produces continuous results that behave reasonably when compared with results for perfectly conducting wedges     

The investigation of the radiation behavior of cells of energy-independent electrically reprogrammable memory based on self-formed conducting nanostructures. I. Mode of information storage

The results of the experimental investigation of the radiation behavior of cells with the use of the electroformed open Si-SiO₂-W sandwich structures as memory cells are presented. Information in these structures is coded by the width of a nanometer insulating gap in the conducting medium appearing on the free end of the silicon dioxide film during electroforming. The current-voltage characteristics determining their state (highly conducting or weakly conducting) before and after the effect of the X-ray radiation with different irradiation doses were monitored for the cells. It is shown that the state of the memory cells determined by the current at a voltage from 1 to 1.5 V does not vary in the mode of information storage (at zero voltages on conducting buses) even at the highest doses of the influence of the ionizing radiation (up to 6 million units). Considerable variations in the currents for voltages lower than 0.5 V are associated with the influence of the radiation on the semiconductor structures of the cells. The mechanisms of conductivity of the memory cells at low (up to 1.5 V) voltages and the mechanisms of their radiation degradation, mainly consisting of charge accumulation in the silicon dioxide layers, are discussed.     

Electrical breakdown of M.O.S. structures and its dependence upon the oxidation process†

The mechanism, by which electrical breakdown of the insulant in M.O.S. structures occurs, is identified ; thermodynamic breakdown, for positive metal voltages ; intrinsic breakdown, for the opposite polarity. Thermodynamic breakdown and the fabrication process are shown to be related to the formation of conducting paths within the oxide. The intrinsic breakdown voltages for devices formed from a particular oxide ore found to be distributed about a mean value ; this value being related to the oxidation temperature and oxide thickness.     

半空间VMD 的磁场垂直分量精确镜像理论解

精确有效计算Sommerfeld型广义积分是分析导电媒质半空间电磁波辐射和散射问题的关键。基于精确镜像理论,详细推导了导电媒质平面上方垂直磁偶极子激励的磁场垂直分量。该表达式快速收敛,易于数值计算,适用于源点与场点为任意位置、导电媒质参数任意的情形。首先利用源点与场点均位于分界面处特殊情形下磁场垂直分量的精确解析表达式,验证了精确镜像理论退化至特殊条件下给出的磁场表达式。然后计算了源与场点位于某一高度的场强。文中结果在可以等效为磁偶极子的小电流圆环场强计算中具有重要的应用价值。     

On the Accuracy of Several Approximate Theories Used in Quantifying the Propagation Effects on Lightning Generated Electromagnetic Fields

The effect of finitely conducting ground on the signature of lightning generated vertical electric fields at ground level was evaluated by numerical solution of Sommerfeld's integrals. Results are presented for distances between 10 m to 1 km from the lightning channel and for ground conductivities in the range of 0.01 and 0.001 S/m. The results obtained from the exact theory are compared with the predictions of several approximate theories available in the literature. Based on that comparison the limits of validity of these approximate theories are obtained.      

Simple expressions for the electric and magnetic field strengths between the elements of an infinite array

Suitable engineering expressions for the electric- and magnetic-field strengths between the elements of an infinite array are derived by employing finitely conducting earth image-theory techniques.     

Perturbations impulsionnelles créées par des câbles ďénergie sur des câbles de transmission de données

This paper presents the study of coupling between multiconductor cables from the multiconductor lines theory and the assumption of perfectly conducting ground. The cables can be excited by generators of arbitrary waveforms and terminated by arbitrary impedances. The medium surrounding the conductors can be homogeneous or inhomogeneous and the conductors can have finite conductivity. Once the used assumptions indicated, we formulate the complete solutions of induced currents and voltages at the ends of the multiconductor line, by using the state variable theory. We give numerous comparisons of numerical results, obtained by our numerical code, with literature (microstrip lines) and experimental results (shielded cables, unshielded RNIS bus).     

On the impedance of a finite-length horizontal wire located near the Earth's surface

Suitable engineering expressions for the external impedance per unit length of a finite-length horizontal electric antenna located near the earth's surface are derived by employing finitely conducting earth-image-theory techniques. The results should be applicable to horizontal wire antennas employed in the ELF band (1 to 3000 Hz).     

Depolarisation of electromagnetic waves backscattered by finitely conducting gently curved surfaces

The vector solution for the field backscattered by a finitely conducting surface with radii of curvature much larger than the incident wavelength obtained by the Stratton-Chu method is expressed in a form which gives insight into the dependence of depolarisation on angle of incidence, incident polarisation and on the electrical and geometrical properties of the backscattering surface.