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A novel high-efficient two-step finite-difference time-domain (FDTD) method is proposed to analyze the lightning-induced voltages on transmission lines (TLs) in this paper. The proposed method includes two steps. The first step is to calculate, using the 2-D FDTD method, electromagnetic fields that are radiated from a vertical lightning channel and illuminate the nearby TLs. The second step is to calculate, using the 3-D FDTD method, the electromagnetic response of the TL that is illuminated by the incident electromagnetic fields added at the total field–scattered field connecting the boundary of the 3-D space. To validate the proposed two-step FDTD method, the results calculated using the two-step FDTD method are compared with those calculated with Agrawal coupling model, and with those calculated using the 3-D FDTD method. The two-step FDTD method shows high computational efficiency in analyzing lightning-induced voltages on TLs. [ABSTRACT FROM AUTHOR]

The evaluation of the lightning performance of overhead lines requires, mainly for distribution lines, the calculation of the voltages induced by nearby lightning strokes hitting the ground. Generally, when calculating lightning-induced voltages using the time-domain approach and the TEM assumption, the most time-consuming stage is the calculation of the source terms of the coupling equations, which means, in turn, the electromagnetic field radiated by the lightning channel. Hence, simplified approaches are still desirable in order to save computational time. Analytical solution of the lighting-originated electric- and magnetic field is available in literature for the case of an ideal transmission-line (TL) return-stroke model with channel-base current having a stepwise waveshape. This paper describes an analytical approach that applies to the case of a general waveshape of the channel-base current, based on the piecewise straight-line approximation, in cylindrical coordinates, which is functional when using the TL return-stroke current model and the Agrawal et al. coupling model. This paper reports the exact solution for the case of trapezoidal waveshape of the current at the base of the channel and the analytical solution for the case of piecewise linear waveform. [ABSTRACT FROM AUTHOR]

This paper deals with the use of the integrated circuit electromagnetic model (ICEM) to analyze, predict, and optimize autocompatibility and electromagnetic emission at chip and system level. ICEM is currently under standardization process (IEC62014- 3). The basic ICEM architecture is composed of a power distribution network model and an internal current source modeling digital activity. Such an approach enables the description of any kind of digital or mixed-signal design. This model is useful either for the IC manufacturer or the system manufacturer. The power distribution network of a printed circuit board (PCB) can be optimized using this model by choosing the number and the right values of decoupling capacitors as well as the size of power planes. The IC manufacturer may check out the autocompatibility of an IC and determine the number of power pins as well as the package to be used. As an example, jitter analysis of an integrated phase-locked-loop can be performed using ICEM. This paper demonstrates that this jitter can be predicted by simulation and that corrective solutions can be provided and checked out before implementation. [ABSTRACT FROM AUTHOR]

In this paper, a time-domain variant of the generalized telegrapher's equations for transient electromagnetic field coupling to a finite-length wire above a lossy half-space is derived. The approach is fully based on the thin-wire antenna theory. The lossy ground effects are taken into account by means of the reflection coefficient approximation. The obtained equations are handled numerically via the Galerkin–Bubnov indirect boundary element method. Computational examples are presented for the case of a single-wire line excited by an electromagnetic pulse excitation source. The obtained results for the induced current along the line are compared with those obtained using 1) the method of moments solution of the electric field integral equation implemented in the numerical electromagnetics code (NEC-4), and 2) the transmission line (TL) theory. It is shown that the results obtained by the proposed method are in excellent agreement with those of NEC-4. It is also shown that the TL approximation yields in general results which are in reasonably good agreement with the full-wave results, especially for the early time response and even beyond the limits of the accuracy of the TL theory. The TL theory can, however, give accurate results only for times before the arrival of the first reflection from the TL terminations and it fails to reproduce accurately the dispersion effects occurring after the first reflection. [ABSTRACT FROM AUTHOR]

The calculation of voltages induced by external electromagnetic fields on multiconductor transmission lines (MTLs) has been the subject of several studies. In this paper, discrete equations for MTLs exposed to incident fields are derived based on the time-domain finite-element method and the backward differentiation formula. Based on these equations, a value-delivery table characterizing the MTLs is presented. Combining this table with modified node analysis formulation, it is convenient for analyzing the responses of transmission lines composed of complex termination networks or complex transmission-lines networks. The validity and efficiency of the proposed algorithm is demonstrated using several examples. Finally, a 1-km 35 kV overhead line above an imperfectly conducting ground is studied, and the influences of ground wire and a metal-oxide arrester to the lightning-induced voltage are both discussed. [ABSTRACT FROM PUBLISHER]

Four model types that could be used to theoretically approximate lightning events currently exist. These are namely gas dynamic (physical) models, electromagnetic models, distributed-circuit models, and “engineering” models. In this paper, a modified transmission line (TL) “engineering” modeling approach, which incorporates the presence of a tall object in the lightning path is adopted. The associated discontinuity at the lightning channel front is treated by introducing reflected and transmitted components, with constituents that are less influential omitted. All computations are performed in the time domain. The considered tall structure is the CN Tower and it is represented by either one, three, or five transmission line sections connected in series. The lightning channel is represented by two more transmission line sections of variable length. The models allow for calculation of current at any height of the CN Tower or the lightning channel and at any time, as needed for determination of the electric and magnetic fields at a distance. The approach is applicable to any other tall structure. [ABSTRACT FROM AUTHOR]

Determination of the distribution of electromagnetic energy inside electrically large enclosed spaces is important in many electromagnetic compatibility applications, such as certification of aircraft and equipment shielding enclosures. The field inside such enclosed environments contains a dominant diffuse component due to multiple randomizing reflections from the enclosing surfaces. The power balance technique has been widely applied to the analysis of such problems; however, it is unable to account for the inhomogeneities in the field that arise when the absorption in the walls and contents of the enclosure is significant. In this paper, we show how a diffusion equation approach can be applied to modeling diffuse electromagnetic fields and evaluate its potential for use in electromagnetic compatibility applications. Two canonical examples were investigated: a loaded cavity and two cavities coupled by a large aperture. The predictions of the diffusion model were compared to measurement data and found to be in good agreement. The diffusion model has a very low computational cost compared to other applicable techniques, such as full-wave simulation and ray-tracing, offering the potential for a radical increase in the efficiency of the solution high frequency electromagnetic shielding problems with complex topologies. [ABSTRACT FROM PUBLISHER]

Magnetic components are widely used in power electronics and are the main cause of electromagnetic couplings. Among them, coils with ferromagnetic cores belong to the class of components that are used the most. However the behavior in terms of radiation and coupling to the environment of these components is not widely explored. This paper defines a more accurate model for coils with toroidal ferrite cores in order to get a better understanding of the coupling they created. Then the effects of the winding layout around a toroidal core are first discussed. It is found that the winding topology is the major parameter controlling both the radiated field pattern and its magnitude. A measurement bench has then been developed to validate the hypothesis made. Finally, numerical and analytic models have been elaborated to predict radiated fields from magnetic components. [ABSTRACT FROM PUBLISHER]

Protection elements are commonly used in electronic systems: digital integrated circuits (ICs) include built-in electrostatic discharge protection devices, and sensitive lines or printed circuit boards traces are often protected using discrete elements, such as clamping or Zener diodes. In order to know if a perturbation is able to disturb or damage ICs, the actual level of signal entering the digital core of the components must be accurately determined, taking into account all the effects of the protection devices. Thus, assessing the perturbation signal at IC core level requires accurate models of the protection elements, even in the case they are inactive. Therefore, this paper focuses on the experimental and theoretical evaluation of the protective behaviors and parasitic effects of these elements. Some limitations of the standard SPICE diode and IBIS models are discussed, and a modeling methodology is presented. Based on a time-domain characterization method associated with a parameter-extraction procedure for enhanced SPICE diode models, the methodology is applied to both discrete and on-chip protection devices and has a good agreement with measurement. [ABSTRACT FROM PUBLISHER]

In this paper, a general domain expression is developed to calculate the horizontal electric field at the ground surface. The expression satisfies stricter conditions than the Cooray–Rubinstein (C-R) and Wait formulae. We proved that the new expression can be reduced into the first approximation of the C-R and Wait formulae. An evaluation that utilized the numerical results obtained by the three formulae was conducted to investigate the error caused by the assumptions made in the C-R and Wait formulae. Finally, the approximate method proposed by Caligaris, Delfino, and Procopio was utilized to evaluate the new formula and the C-R formula through comparison with the results obtained conventionally using the C-R formula. [ABSTRACT FROM PUBLISHER]

A new method for the numerical simulation of the stochastic electromagnetic environment of a mode-stirred chamber is presented in this paper. This method is based on the plane-wave integral representation for the fields and uses a Monte Carlo simulation to replace the analytical integration by numerical summation. Therefore, a field generator is implemented as a program. The numerically generated field distributions and spatial correlation functions are compared to the analytical solutions for the validation of the field generator. With this generator, the field coupling to a simple transmission-line structure can be numerically simulated. The coupled current or voltage has to be regarded as a stochastic value as well, and therefore, parameters like the mean value and the standard deviation along the line are calculated. For the special case of a matched line, an analytic solution is introduced in order to validate the numerical results. The simulation also allows for investigating the statistical distribution and correlation of the coupled current along the transmission line. Numerous simulated results are compared with measurements. [ABSTRACT FROM PUBLISHER]

This paper presents SPICE models for the prediction of effects on shielded cables induced by nonuniform fields. Based on the transmission line theory, these models can be utilized to analyze shielded cables terminated with nonlinear or time-varying loads excited by nonuniform fields in the time domain. Two examples, a coaxial shielded cable and a two-parallel-wire shielded cable, both inside a cavity with a slot excited by an incident wave, are studied with the proposed models. The finite-difference time-domain method is employed to calculate the excitation fields of the cables, and then, the SPICE models are utilized to obtain the disturbances induced by the incident wave on the cables. The results obtained by the proposed models agree well with those obtained through other methods. [ABSTRACT FROM AUTHOR]

Near-electric-field and magnetic-field probes are used for a wide variety of applications. Accurate measurement of the fields, however, requires an accurate model of the receiving characteristic of the probe. The receiving characteristic for a reciprocal near-field probe can be calculated from its transmitting characteristic. This receiving characteristic can be used to evaluate the quality of the probe and to compensate for the effect of the probe on the measured field, thereby allowing the electric and magnetic fields to be found accurately from the measurements. In the following paper, methods of evaluating near-field probes using reciprocity are derived and are applied to a typical loop probe in order to compensate near-field measurements over a device under test. [ABSTRACT FROM AUTHOR]

Radiated fields in the far-field zone of a small, thin-wire, square loop placed centrally above a finite image plane are analyzed by a set of 3-D electromagnetic simulations. The impact of a finite image plane on the maximum radiated fields and on the shape of the radiation pattern is addressed. The image theory is extended to include the modeling of finite image planes by modifying the contribution of the image loop to the total radiated fields as a function of two parameters: the size of the plane and the distance between the loop and the plane. The proposed analytic solution provides a fast and simple method to calculate radiated fields in the far-field zone of electrically small magnetically driven sources above a finite image plane. [ABSTRACT FROM AUTHOR]

We derive equations to calculate the number of samples (tuner positions) required to achieve a certain inhomogeneity for the maximum of a rectangular field strength component with given confidence in reverberation chambers. Perfect and limited reverberation are investigated. The results are in good agreement with unreferenced values found in reverberation standards, e.g., IEC 61000-4-21. They can be used to a priori predict the required number of independent samples from the quality factor and the chamber volume only. Evidence is given that current homogeneity limits in standards (3 dB, IEC 61000-4-21) are inconsistent with the minimum number of samples to use (namely 12) at high frequencies. [ABSTRACT FROM AUTHOR]

Using measured wideband electric field waveforms and the Hertzian dipole (HD) approximation, we estimated peak currents for 48 located compact intracloud lightning discharges (CIDs) in Florida. The HD approximation was used because 1) CID channel lengths are expected to range from about 100 to 1000 m, and in many cases can be considered electrically short and 2) it allows one to considerably simplify the inverse source problem. Horizontal distances to the sources were reported by the U.S. National Lightning Detection Network (NLDN), and source heights were estimated from the horizontal distance and the ratio of electric and magnetic fields. The resultant CID peak currents ranged from 33 to 259 kA with a geometric mean of 74 kA. The majority of NLDN-reported peak currents for the same 48 CIDs are considerably smaller than those predicted by the HD approximation. The discrepancy is primarily because NLDN-reported peak currents are assumed to be proportional to peak fields, while for the HD approximation, the peak current is proportional to the peak of the integral of the electric radiation field. An additional factor is the limited (400 kHz) upper frequency response of the NLDN. [ABSTRACT FROM PUBLISHER]

Over the last 20 years, the wireless technology has known a large development in terms of devices and services, accompanied consequently by considerable doubts about the level of exposure to the electromagnetic fields radiated by these systems. An intermediate step in the assessment of the real exposure is to statistically model the input power delivered to these personal devices during an uplink transmission. In this spirit, we propose a systematic methodology for the characterization of the variability of the delivered input power for given propagation conditions. This methodology first addresses the influence of the personal devices relative positioning, with respect to the user's body on the antennas performance as well as on the exposure level. Second, it add-resses the sensitivity of the input power to the characteristics of the propagation channel. The exposure levels have been investigated from specific absorption rates computed using finite-difference time-domain simulations on a realistic numerical model of child bodies. The input power is directly related to the antenna radiation pattern and to the local propagation scenario, through effects such as body obstruction and multipath diversity. The statistical analysis shows that the delivered input power can be modeled by an inverse Gaussian or a log-normal distribution. [ABSTRACT FROM AUTHOR]

In this study, we use a statistical approach to treat a risk analysis of an EMC default. This approach relies upon reliability methods from probabilistic engineering mechanics. An estimation of a probability of failure (i.e., probability that the induced current by crosstalk causes a malfunction of a device connected at the end of a cable) and a sensitivity analysis of this probability of failure is carried out by taking into account uncertainties on input parameters. The reliability methods introduced in this study allow to compute a probability of failure with a relative low computational cost compared to Monte Carlo simulation. [ABSTRACT FROM AUTHOR]

A simple model of intrinsic stochastic electromagnetic fields and a simple transmission line model are combined to analytically derive closed-form expressions for the average field coupling to a transmission line. The results are valid under the assumptions of transmission line theory for a line with general load resistances. The theoretical analysis starts with the calculation of the mean squared current magnitude along the line and at the ends. This result is transferred to the coupled voltage. Then, the characteristics of the statistic distribution can be used to calculate other important parameters like the variance or the maximum value. [ABSTRACT FROM AUTHOR]

An equivalent circuit for the analysis of the interaction between an electromagnetic field and a thin graphene sheet is derived, based on a local anisotropic model of the graphene conductivity, valid at frequencies below the THz range. Due to the anisotropic properties, the equivalent circuit is a four-port network which couples the fundamental TE and TM polarizations. The possible effects of electrostatic and/or magnetostatic bias are included and the equivalent circuit is next used to investigate the shielding properties of graphene layers against impinging plane waves. While the possibility of tuning the graphene conductivity leads to interesting properties of electronic control of shielding perfomance, the proposed equivalent circuit represents a very simple tool for the relevant analysis and design. [ABSTRACT FROM AUTHOR]

In this study, the impact of Wi-Fi access points is investigated in terms of electromagnetic field exposure evaluations. Installations, typically present in common living contexts, have been analyzed by means of both wideband and narrow-band measurements and simulation-prediction tools. The obtained results show that exposure due to these systems is compliant with the limits provided by regulation. [ABSTRACT FROM AUTHOR]

Describes the statistical electromagnetic field model and power fluxes in overmoded, leaky, external driven cavity. Exploration of various modeling combinations of chi square distributions; Advantage of two chi square models; Use of statistically generated field models as drivers of cable codes.

Examines a mathematical model for calculation of lightning generated electromagnetic fields at different depths below ground surface. Calculation of underground electromagnetic fields to surface fields; Illustration of electric and magnetic field variation; Intention of relating underground fields to counterparts at the surface.

Analysis of channel base current functions with specific reference to new channel base current (NCBC) function is reported. The main concern has been of adjusting the maximum time rate of change of lightning current (di/dt)max along with time to crest t_m. A new ratio (maximum time rate of change of lightning current (di/dt)max by average time rate of change of lightning current (di/dt)avg) has been defined. The critical numerical value for this ratio is identified as 1.7 for NCBC function. The performance of NCBC function is compared with Heidler’s function in the wave front region. [ABSTRACT FROM AUTHOR]

The correspondence discusses a correction to the thin-wire algorithm developed in a previous publication. By employing a slightly different choice of the operational parameters of the computation, the wave speed of transverse electromagnetic propagation along a thin wire is closer to the speed of light than in the original model. Results are shown for the propagation properties of a canonical square coaxial transmission-line. [ABSTRACT FROM AUTHOR]