Showing papers in "IEEE Transactions on Electromagnetic Compatibility in 1993"
TL;DR: In this paper, a modeling procedure that permits calculation of lightning-induced voltages on overhead lines starting from the channel-base current is discussed, which makes use of a coupling model already presented in the literature, based on transmission line theory, for field-to-overhead line coupling calculations.
Abstract: 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. >
373 citations
TL;DR: In this paper, an equivalent formulation is derived in which the source terms (or forcing functions) are expressed in terms of the magnetic excitation field, which is particularly useful for evaluating field-to-transmission-line coupling when the exciting field is determined experimentally, since only the measurement of the electric field is necessary.
Abstract: Different formulations of the field-to-transmission-line coupling equations are reviewed and discussed. An equivalent formulation is derived in which the source terms (or forcing functions) are expressed in terms of the magnetic excitation field. This formulation is particularly useful for evaluating field-to-transmission-line coupling when the exciting field is determined experimentally, since only the measurement of the electric field-generally easier to measure than the electric field-is necessary. >
266 citations
TL;DR: A set of time-domain characterizations that can efficiently describe wireband antennas is proposed in this article, where the experimentally measured responses of transverse electromagnetic horn antennas are used to evaluate the utility of these characterizations.
Abstract: A set of time-domain characterizations that can efficiently describe wireband antennas is proposed. The experimentally measured responses of transverse electromagnetic horn antennas are used to evaluate the utility of these characterizations. Comparisons are made between the antennas' frequency-domain response and their time-domain characterizations. The comparisons show that the time-domain characterizations can provide significant insight into an antenna's behavior as well as providing a means to accurately compare two or more different antennas. >
112 citations
TL;DR: The authors demonstrate that staircased approximations to curved or oblique electromagnetic interfaces yield poor accuracy unless the user has truly unlimited computer resources for two simple geometries: a conducting strip and a circular conducting cylinder.
Abstract: The authors demonstrate that staircased approximations to curved or oblique electromagnetic interfaces yield poor accuracy unless the user has truly unlimited computer resources for two simple geometries: a conducting strip and a circular conducting cylinder. Conformal meshing reduces by a factor of four the resolution required in each direction. A conformally meshed circular cylinder model yields good radar cross section (RCS) predictions with only eight cells per wavelength. >
107 citations
TL;DR: In this article, approximate formulas for the coupling parameters of cables with single-braided shields are presented based on a qualitative analysis of the coupling mechanisms; these qualitative approaches have been verified and adjusted to reality by measuring many different braids.
Abstract: Approximate formulas for the coupling parameters of cables with single-braided shields are presented. The derivation of the formulas is based on a qualitative analysis of the coupling mechanisms; these qualitative approaches have been verified and adjusted to reality by measuring many different braids. Assuming that the shields are grounded or open ended, the approximation formulas yield the high-frequency-optimizing equation, which permits the design of optimized single-braided shields. >
102 citations
TL;DR: The theoretical results for the signal path loss along the streets are compared with measurements done in New York and Tokyo for various values of the propagation parameters and indicate that the UTD formulation is a good model for such urban communication applications.
Abstract: A three-dimensional propagation model for microcellular communications in an urban street scene is presented. The model is based on the uniform theory of diffraction (UTD) and takes into account multiple wall-to-wall, wall-to-ground, and ground-to-wall reflections, the diffraction from corners of buildings, and subsequent reflections from such diffracted signals. The ray geometry is made extremely complex by the presence of ground reflections and the many combinations of sequences of reflections or diffractions from walls, edges, and ground. At each reflection or diffraction point, the local ray-fixed coordinate system or edge-fixed coordinate system is used together with appropriate dyadic reflection or diffraction coefficient matrices. The theoretical results for the signal path loss along the streets are compared with measurements done in New York and Tokyo for various values of the propagation parameters. Agreement with these measurements indicates that the UTD formulation is a good model for such urban communication applications. >
95 citations
TL;DR: In this paper, the EM plane-wave shielding properties of anisotropic laminated composites are analyzed, based on a model that treats each lamina as a homogeneous and an isotropic sheet and then uses a method that cascades the wave-transmission matrices in the computation, Numerical results are presented for graphite/epoxy laminates.
Abstract: The EM plane-wave shielding properties of anisotropic laminated composites are analyzed, based on a model that treats each lamina as a homogeneous and anisotropic sheet and then uses a method that cascades the wave-transmission matrices in the computation, Numerical results are presented for graphite/epoxy laminates. In particular, the parameters that influence the shielding effectiveness, such as material properties, laminate thickness, fiber orientation and anisotropy of laminates, and angle and polarization of incident wave, are investigated in detail. For design purposes, empirical formulas are also proposed to estimate the shielding effectiveness of the laminated composites in the lower frequency range. >
86 citations
TL;DR: In this article, the authors show that the physics of the delta-I noise is more complex and that it is related to wave propagation effects, and that the inductive effects are important only for slower transients.
Abstract: Delta-I noise is the voltage induced between the power conductors (e.g. the ground and the V/sub cc/ planes) when a circuit connected between them switches from one state to another. The authors show that the physics of the noise is more complex, and that it is related to wave propagation effects. Delta-I noise should be present not only in integrated circuits (chips), but also in multilayered boards, where it should be pronounced when the transients are of the order of 1 ns or less. Investigation of the delta-I noise is carried out for a simplified model of power planes, using a wire-antenna numerical simulation program. The model includes the wave propagation effects, as well as radiation, but it does not include the effects of the dielectric filling the space between the planes. The results of the analysis clearly show that the inductive effects are important only for slower transients. For fast digital circuits the power planes actually form a resonator,which can have a high quality factor, and the delta-I noise can build up to very high voltage levels. >
69 citations
TL;DR: In this paper, the electromagnetic radiation from a VLSI chip package and heatsink structure is analyzed by means of the finite-difference-time-domain (FDTD) technique.
Abstract: The electromagnetic radiation from a VLSI chip package and heatsink structure is analyzed by means of the finite-difference-time-domain (FDTD) technique. The dimensions of a typical configuration call for a multizone gridding scheme in the FDTD algorithm to accommodate fine grid cells in the vicinity of the heatsink and package cavity and sparse gridding in the remainder of the computational domain. The issues pertaining to the effects of the heatsink on the overall radiative capacity of the configuration are addressed. Analyses are facilitated by using simplified heatsink models and by using dipole elements as sources of electromagnetic energy to model the VLSI chip. The potential for enhancement of spurious emissions by the heatsink structure is illustrated. For heatsinks of typical dimensions, resonance is possible within the low gigahertz frequency range. The exploitation of the heatsink as an emissions shield by appropriate implementation schemes is discussed and evaluated. >
68 citations
TL;DR: In this article, a model enabling the computation of the coupling distribution and other statistical parameters of interest, such as coupling distribution's expectation and standard deviation, is developed, and its results compare well with computations based on the analytical model.
Abstract: The authors point out that the random positioning of wires, as described here, frequently occurs in practice since the relative positions of the wires are often unknown. Consequently, the problem of crosstalk has a probabilistic nature and needs to be analyzed accordingly. The problem of two wires whose heights above ground and whose distance of separation are known only probabilistically is considered. A model enabling the computation of the coupling distribution and other statistical parameters of interest, such as the coupling distribution's expectation and standard deviation, is developed. A simulation was performed, and its results compare well with computations based on the analytical model. >
59 citations
TL;DR: In this article, a numerical technique, called the modified Powell method, is used to design radar-absorbing materials (RAMs) made up of several dielectric layers, usually on top of a conducting (ground) plane.
Abstract: A numerical technique, called the (modified) Powell method, is used to design radar-absorbing materials (RAMs) made up of several dielectric layers, usually on top of a conducting (ground) plane. The absorption of RF energy occurs mostly in the last layer. The other layers are used to match the wave impedance of the RAM to that of the medium on which the radiation is incident, for the desired angles of incidence, frequencies, and polarizations. The technique is very flexible, allowing the design of RAMs tailored for specific applications or general use. One important example is the design of RAMs that can maintain a minimum absorption rate from normal to almost grazing incidence, over a specified frequency bandwidth. >
TL;DR: In this paper, the FDTD method is used to model and predict the radiation patterns of a monopole antenna mounted on the bottom of a perfectly conducting helicopter structure, and the computed radiation patterns are compared with measurements to demonstrate the accuracy of the method.
Abstract: The finite-difference-time-domain (FDTD) method is reviewed and then used to model and predict the radiation patterns of a monopole antenna mounted on the bottom of a perfectly conducting helicopter structure. The computed radiation patterns are compared with measurements to demonstrate the accuracy of the FDTD method. To study the effect of antenna interference, a second monopole antenna is mounted on the structure and the patterns are recalculated. The perfectly conducting helicopter model is then replaced by a partially composite/partially conducting material structure and the electromagnetic fields penetrating the structure from an incident plane wave are analyzed. A preprocessing geometry program, GEOM, is used to generate an FDTD geometry model, assuming solid surface helicopter structure. >
TL;DR: In this article, an exact formulation of surface impedances, starting from Fresnel reflection coefficients for oblique incidence of the incident wave, is introduced into an FDTD algorithm where it is converted into a surface-impedance boundary condition (SIBC) for vertical or horizontal polarizations of locally plane waves.
Abstract: The authors point out that modeling of interfaces between two media, using time-domain surface impedances, permits one to reduce the discretization volume in the finite-difference-time-domain (FDTD) technique. The method presented here is based on an exact formulation of surface impedances, starting from Fresnel reflection coefficients for oblique incidence of the incident wave. The concept, valid for homogeneous and frequency-independent media, is then introduced into an FDTD algorithm where it is converted into a surface-impedance boundary condition (SIBC) for vertical or horizontal polarizations of locally plane waves. Two- and three-dimensional results are compared to those computed with classical FDTD or Fresnel reflection coefficients involving a Fourier transform. >
TL;DR: A detailed analysis of the transient response of an electromagnetic pulse (EMP) and a Gaussian pulse in anisotropic laminated composites is presented in this paper, where both the equivalent transmission line circuit (ETLC) model and the finite-difference-time-domain (FDTD) method are adopted in the time-domain analysis.
Abstract: A detailed analysis of the transient response of an electromagnetic pulse (EMP) and a Gaussian pulse in anisotropic laminated composites is presented. To this end, both the equivalent transmission line circuit (ETLC) model and the finite-difference-time-domain (FDTD) method are adopted in the time-domain analysis. Numerical results are presented for graphite/epoxy laminates, based on a model which treats each lamina as a homogeneous and anisotropic sheet. The factors that influence the transient response of anisotropic laminated composites, such as laminate thickness, fiber orientation, and the angle, frequency contents, and polarization of the incident wave, are also investigated. >
TL;DR: In this article, a problem of practical interest, related to crosstalk, is formulated to be solved using the finite element method (FEM) for solving the problem in all its aspects including the determination of parasitic effects.
Abstract: In a printed circuit board environment, the solution domain is highly inhomogeneous, and analytic expressions for design parameters are very difficult to obtain, even for the simplest configuration. The finite element method (FEM) offers an attractive alternative for solving the problem in all its aspects including the determination of parasitic effects. A problem of practical interest, related to crosstalk, is formulated to be solved using the FEM. The technique is first applied to obtain the field distribution, and then the field is used to calculate transmission line parameters of conducting tracks on printed circuit boards. FEM is used to solve a radiation problem in three dimensions. The solution is used to predict far-field radiation levels of electronic equipment from near-field measurements. >
TL;DR: In this paper, a method for measuring power line impedances using two current probes is examined, which is characterized by good isolation of the measurement equipment from the power line voltage and by the capability of measuring power lines impedances between any pair of power plug terminals.
Abstract: A method for measuring power line impedances using two current probes is examined. This method is characterized by good isolation of the measurement equipment from the power line voltage and by the capability of measuring power line impedances between any pair of power-plug terminals. The use of this two-current probe method with the model described is effective in measuring power line impedances from 0.5 MHz to 100 MHz. Using purely resistive loads for calibration, the error is less than 5% for frequencies below 100 MHz, and less than 20% for frequencies between 100 MHz and 500 MHz. The error in an impedance measurement increases with the magnitude of the load impedance. >
TL;DR: In this paper, the application of the finite-difference-time-domain (FDTD) method to propagation through a highly conductive nonlinear magnetic material is described, and the effects of the high conductivity and magnetic material nonlinearity on the stability of the FDTD calculation are investigated.
Abstract: The application of the finite-difference-time-domain (FDTD) method to propagation through a highly conductive nonlinear magnetic material is described. The FDTD calculations will require changing the permeability of the material at each time step based on the value of the magnetic field at the previous time step. The effects of the high conductivity and magnetic material nonlinearity on the stability of the FDTD calculation is investigated. Stability requires reduction of the time-step size to well below the Courant limit. Accuracy is demonstrated by comparison with previously published results. >
TL;DR: The correlation between different methods for the characterization of shielding materials is discussed in this paper, where it is found that a good agreement is obtained using basic methods, such as a four-point resistance measurement, or standard shielding effectiveness methods and using other methods allowing a quick control in the field during injection molding process.
Abstract: The correlation between different methods for the characterization of shielding materials is discussed. It is found that a good agreement is obtained using basic methods, such as a four-point resistance measurement, or standard shielding effectiveness methods and using other methods allowing a quick control in the field during injection moulding process. >
TL;DR: In this article, the authors studied the effect of coupling through a circular aperture in the shield of a coaxial air line in a reverberation chamber over wide frequency ranges, and made recommendations for improvements in the measurements and theory for achieving the closer agreement that would be desirable for an artifact standard for shielding effectiveness measurements.
Abstract: Coupling through a circular aperture in the shield of a coaxial air line is studied theoretically and experimentally. Polarizability theory is used to compute the effective dipole moments that excite the coaxial line in the internal region. Measurements of shielding effectiveness were made in a reverberation chamber over wide frequency ranges. Agreement between theory and measurements is generally within +or-10 dB. Recommendations for improvements in the measurements and theory are made for achieving the closer agreement that would be desirable for an artifact standard for shielding effectiveness measurements. >
TL;DR: In this article, the problem of radiated emission from printed circuit boards (PCBs) is theoretically and experimentally investigated, and the solution of the integral equations for the current distribution, derived from the problem formulation, is numerically achieved by the method of moments.
Abstract: The problem of the radiated emission from printed circuit boards, (PCBs) is theoretically and experimentally investigated. Differential mode and common mode currents are separately studied by means of a rigorous method based on proper Green's functions. The solution of the integral equations for the current distribution, derived from the problem formulation, is numerically achieved by the method of moments. Simulated results are in good agreement with measurements. The final products of this study are masks that establish the maximum allowable currents or voltage values as a function of frequency to comply with CISPR regulation. >
TL;DR: In this paper, the ambient electric and magnetic fields as well as the electromagnetic fields associated with video display terminals (VDTs) at 150 offices were measured, and the authors determined the general level of the various electromagnetic parameters in offices and established a technical base for a case referent study of skin symptoms among VDT workers.
Abstract: The ambient electric and magnetic fields as well as the electromagnetic fields associated with video display terminals (VDTs) at 150 offices are measured. The aim of the study is to determine the general level of the various electromagnetic parameters in offices and establish a technical base for a case referent study of skin symptoms among VDT workers. The median value of the 50-Hz background field in the 150 offices is 0.07 mu T. Seven of the offices have background levels higher than 0.5 mu T, which is high enough to cause distortion of the picture on the screen. The dominant source for electric fields in the ELF range is electric equipment in the office, not the VDTs. The equivalent surface potential is less than 0.5 kV for 63% of the measured VDTs. The computer monitor is a major source of magnetic fields in the offices. The median value of the magnetic field in the ELF range in front of the VDT is 0.21 mu T, and in the VLF range it is 0.03 mu T. >
TL;DR: In this article, a method for decomposing an asymmetric structure into two substructures is presented, where one substructure contains the attributes of symmetry while the remainder or residual substructure contain the attributes or residuals of asymmetry.
Abstract: A method for decomposing an asymmetrical structure into two substructures is given. One substructure contains the attributes of symmetry while the remainder or residual substructure contains the attributes of asymmetry. The decomposition is done in such a way that the superposition of the radiated electromagnetic fields of the decomposition substructures gives the radiated fields of the original structure. Although the substructures can, by superposition, be used to compute the total radiated fields of the original structure, the primary purpose of the decomposition technique is to provide insight into methods for reducing the emissions of each substructure and consequently those of the original structure. In many cases the emissions of the asymmetric substructure are the dominant contributors to the total emissions of the original structure. In this case, the decomposition substructures allow direct insight into the reduction of the total emissions that was previously available only for the symmetric substructure. >
TL;DR: In this paper, a wideband measurement system was developed for the evaluation of the backscatter performance of dissipative macrostructures in an ordinary room environment on metal plates as well as samples of pyramidal absorbing material.
Abstract: A wideband time-domain measurement system has been developed for the evaluation of the backscatter performance of dissipative macrostructures. Backscatter measurements have been performed in an ordinary room environment on metal plates as well as samples of pyramidal absorbing material. The backscattering performance of pyramidal absorbers is evaluated in the 50- to 1000-MHz frequency range with a varying incident field angle of incidence. In the case of rectangular metal plates, numerically generated results are compared with measured data in order to gauge the accuracy of the system. >
TL;DR: In this paper, the level of spurious radiation from microstrip interconnects, which are modeled as either single or asymmetric parallel microstrip lines terminated by arbitrary complex load impedances, is investigated.
Abstract: The level of spurious radiation from microstrip interconnects, which are modeled as either single or asymmetric parallel microstrip lines terminated by arbitrary complex load impedances, is investigated. The calculation of the spurious radiation requires a knowledge of the current distributions on the microstrip lines, and the first step is to compute these distributions efficiently. This is carried out by using the method of moments in conjunction with closed-form spatial domain Green's functions that circumvent the need for time-consuming evaluation of Sommerfeld integrals. Once the current distributions on the etches have been obtained, the level of spurious radiation, which is defined as the radiated power crossing the plane parallel to the plane of interconnects, is calculated. The dependence of the spurious radiation on the lengths of the lines and on the termination impedances of the etches is also studied. >
TL;DR: In this article, a simple, rapid, and accurate numerical method is presented for calculating the shielding effectiveness and the light transmittance of multilayered media, which can be applied at any frequency, for vertical or oblique incidence.
Abstract: A simple, rapid, and accurate numerical method is presented for calculating the shielding effectiveness and the light transmittance of multilayered media. A uniform treatment is used to obtain the shielding effectiveness of the layers at microwave frequencies and their light transmittance at optical frequencies. The method is completely general and does not involve any approximation. It can be applied at any frequency, for vertical or oblique incidence, to lossless or lossy, isotropic or anisotropic media consisting of any number of dielectric and metallic layers. In order to illustrate the versatility of the method, the shielding effectiveness and the light transmittance of two different structures consisting of a gold film deposited over a plastic substrate and of a plastic substrate sandwiched between two gold films are analyzed under different conditions. >
TL;DR: In this article, an approach for analyzing the electromagnetic performance of bounded-wave nuclear electromagnetic pulse (NEMP) simulators is presented. But this method relies on a priori knowledge as much as possible.
Abstract: The author discusses an approach for analyzing the electromagnetic performance of bounded-wave nuclear electromagnetic pulse (NEMP) simulators. This method is extremely efficient and enables even the largest simulators to be analyzed. Typical bounded-wave EMP simulators are composed of flat-plate transmission-line sections approximated by wires. Using a priori knowledge as much as possible, the method presented obtains the current in the wave launcher's wires from an approximation of the current in a conical-plate wave launcher that generates a spherical TEM wave propagating along the radial direction. This method uses TEM-like currents obtained by approximating the TEM-mode current in the conical-plate wave launcher. The transient electromagnetic fields within the simulator's working volume are then readily computed by using efficient and analytical time-domain expressions for the fields generated by the wires. Expressions for the early-time fields and the impedance of a conical wire-mesh wave launcher are derived. Numerical results are presented for EMPSIS, a triangular-plate simulator for ships. >
TL;DR: In this article, a mixed (scalar and vector) potential surface integral equation formulation was employed in conjunction with the method of moments to predict the radiated emission from arbitrarily shaped printed circuit traces.
Abstract: A mixed (scalar and vector) potential surface integral equation formulation, developed for microstrip antennas, is employed in conjunction with the method of moments to predict the radiated emission from arbitrarily shaped printed circuit traces. Computed currents and radiated fields for a typical trace configuration in the form of a rectangular loop loaded by low- or high-impedance lumped loads indicate good agreement with transmission line theory and/or elementary loop antenna analysis, when the trace size is electrically small. Computed results are presented to highlight the radiation and coupling due to common-mode currents. >
TL;DR: The wire TEM (WTEM) cell as discussed by the authors is similar to a TEM cell but has an inner wire array rather than a conducting septum, and the transmission line is terminated in a resistor array at low frequencies, and in anechoic material at higher frequencies.
Abstract: The subject of this study is the analysis of a device for electromagnetic interference (EMI) measurements; the structure, called the wire TEM (WTEM) cell, is similar to a TEM cell but has an inner wire array rather than a conducting septum. The transmission line is terminated in a resistor array at low frequencies, and in anechoic material at higher frequencies. The device is designed specifically to provide a high field uniformity in the test region. The performance of the WTEM cell is compared with that of TEM striplines. An enlarged quasi-static frequency band is available with the WTEM cell; moreover the coupling of the device under test with the structure is lower. The performance of the device as a standard EM field generator has been predicted by a theoretical quasi-static analysis and estimated by measurements over a wide frequency band. >
TL;DR: In this paper, the capacitance and charge distribution of an isolated hollow conducting cylinder of finite length are evaluated based on replacing the charged cylinder by a charged filament along its axis and on the moment method formulation.
Abstract: The capacitance and charge distribution of an isolated hollow conducting cylinder of finite length are evaluated. The analysis is based on replacing the charged cylinder by a charged filament along its axis and on the moment method formulation. The numerical results are compared with those determined from the evaluation of the integral for the potential and data of R.F. Harrington (see Field Computation by Moment Method, Krieger Publishing Company, 1985). The method is used to evaluate the variation of capacitance and charge distribution of a hollow conducting truncated cone with its smaller radius. The validity of the analysis is established from a comparison of data for the smaller radius approaching the large radius when the truncated cone becomes a cylinder. >
TL;DR: In this paper, a finite-difference-time-domain (FDTD) method for the efficient solution of wideband electromagnetic phenomena is described, which uses a second-order Lax-Wendroff finitedifference algorithm in conjunction with the method of flux-corrected transport (FCT) to suppress problems with dispersion that occur when solving Maxwell's equations using the standard secondorder Yee FDTD algorithm.
Abstract: A finite-difference-time-domain (FDTD) method for the efficient solution of wideband electromagnetic phenomena is described. The algorithm uses a second-order Lax-Wendroff finite-difference algorithm in conjunction with the method of flux-corrected transport (FCT) to suppress problems with dispersion that occur when solving Maxwell's equations using the standard second-order Yee FDTD algorithm. Results comparing the accuracy of the Lax-Wendroff/FCT method and the Yee algorithm for propagating pulsed-type plane waves are given. >