Showing papers in "IEEE Transactions on Electromagnetic Compatibility in 2006"

Feature selective validation (FSV) for validation of computational electromagnetics (CEM). part I-the FSV method

Abstract: A goal for the validation of computational electromagnetics (CEM) is to provide the community with a simple computational method that can be used to predict the assessment of electromagnetic compatibility (EMC) data as it would be undertaken by individuals or teams of engineers. The benefits of being able to do this include quantifying the comparison of data that has hitherto only been assessed qualitatively, to provide the ability to track differences between model iterations, and to provide a means of capturing the variability and range of opinions of groups and teams of workers. The feature selective validation (FSV) technique shows great promise for achieving this goal. This paper presents a detailed analysis of the FSV method, setting it firmly in the context of previous comparison techniques; it suggests the relationship between validation of graphically presented data and the psychology of visual perception. A set of applicability tests to judge the effectiveness of computer-based CEM validation techniques is also proposed. This paper is followed by a detailed comparison with visual assessment, which is presented in Part II

Feature selective validation (FSV) for validation of computational electromagnetics (CEM). part II- assessment of FSV performance

Abstract: The feature selective validation (FSV) method has been proposed as a technique to allow the objective, quantified, comparison of data for inter alia validation of computational electromagnetics. In the companion paper "Feature selective validation for validation of computational electromagnetics. Part I-The FSV method," the method was outlined in some detail. This paper addresses two specific issues related to the implementation of the FSV method, namely "how well does it produce results that agree with visual assessment?" and "what benefit can it provide in a practical validation environment?" The first of these questions is addressed by comparing the FSV output to the results of an extensive survey of EMC engineers from several countries. The second is approached via a case study analysis

Comparisons of computed mobile phone induced SAR in the SAM phantom to that in anatomically correct models of the human head

Abstract: The specific absorption rates (SAR) determined computationally in the specific anthropomorphic mannequin (SAM) and anatomically correct models of the human head when exposed to a mobile phone model are compared as part of a study organized by IEEE Standards Coordinating Committee 34, Sub-Committee 2, and Working Group 2, and carried out by an international task force comprising 14 government, academic, and industrial research institutions. The detailed study protocol defined the computational head and mobile phone models. The participants used different finite-difference time-domain software and independently positioned the mobile phone and head models in accordance with the protocol. The results show that when the pinna SAR is calculated separately from the head SAR, SAM produced a higher SAR in the head than the anatomically correct head models. Also the larger (adult) head produced a statistically significant higher peak SAR for both the 1- and 10-g averages than did the smaller (child) head for all conditions of frequency and position.

Voltages induced on an overhead wire by lightning strikes to a nearby tall grounded object

Abstract: The aim of this study was to identify conditions under which the presence of tall strike object can serve to increase or decrease lightning-induced voltages on a nearby overhead wire. We examined the ratios of magnitudes of lightning-induced voltages on the overhead wire for the cases of strikes to a tall object and to flat ground as a function of distance from the lightning channel d, current reflection coefficients at the top of the strike object rhotop and at the bottom of the strike object rhobot, the current reflection coefficient at the channel base (in the case of strikes to flat ground) rhogr, and the return stroke speed v. Lightning-induced voltages were computed using the finite-difference time-domain (FDTD) method. The transmission line (TL) model was used to find the distribution of current along the lightning channel and the strike object. The ratio of magnitudes of lightning-induced voltages for tall-object and flat-ground cases increases with increasing d (ranging from 40--200 m), decreasing rhobot(<1), decreasing rho top (<0, except for the case of rhobot=0), and decreasing v (

Requirements for an effective reverberation chamber: unloaded or loaded

Abstract: In this paper, we present two versions of a threshold metric for the purpose of accessing the effectiveness of a reverberation chamber. One metric is based on the chamber quality factor (Q), and the other is based on the volume of the loaded reverberation chamber. These metrics are baseline quantities that must be exceeded in order to have an effective reverberation chamber. These threshold metrics are obtained from two different approaches. The first approach is based on a free-space transmission formulation and the scalar mean power density associated with the "stirred energy" in the chamber and requires that the stirred energy exceeds the unstirred energy throughout most of the chamber volume. The second approach is obtained by requiring that the amplitude of the electric (or magnetic) field satisfies the expected Rayleigh probability density function throughout most of the chamber volume. We present an application of these metrics for the case of a reverberation chamber loaded with spheres composed of lossy materials

Approximation of aging effect on dielectric tissue properties for SAR assessment of mobile telephones

Abstract: In electromagnetic dosimetry of children heads for mobile telephones, the dielectric properties of biological tissues for adults are so far being used due to the lack of the ones of children. In this paper, we derived an empirical formula according to Lichtenecker's exponential law for the complex permittivity of various tissues as a function of the hydrated rate or the total body water (TBW). We first examined its validity using the data measured by Peyman et al. for rats, and then applied the formula to the dielectric properties of 7-year-old and 3-year-old child head models by means of the relationship between the TBW and the age. With the dielectric properties for children derived in such an approach, we analyzed numerically the spatial peak specific absorption rate (SAR) for a 900-MHz mobile telephone in adult and child head models. As a result, we found that the dielectric properties for children do not affect significantly the 1- or 10- g averaged spatial peak SAR as well as the penetration depth. The finding could be qualitatively explained as cancellation of the increased conductivity and decreased electric field penetrating into the tissue because of the same degree of increase between the conductivity and permittivity in children compared to adults. Even in an extreme case, the age effect on the spatial peak SAR of dielectric properties is still within 10%.

An active EMI filtering technique for improving passive filter low-frequency performance

Abstract: In recent years, there has been considerable interest in the development and applications of active electromagnetic interference (EMI) filters. An active EMI filter (AEF) for integrated power electronics module (IPEM) is proposed in this paper, where large passive EMI filter is replaced by small passive components and active op-amp circuit. The technique is appropriated when improved attenuation is required at relatively low frequencies and the high-frequency filtering requirements are easily met. The effectiveness of the proposed circuit has been verified by experimental results. It is demonstrated that the proposed approach is most effective in a case where it is desirable to minimize the amount of passive components in the filter

Improving the convergence of vector fitting for equivalent circuit extraction from noisy frequency responses

Abstract: The vector fitting (VF) algorithm has become a common tool in electromagnetic compatibility and signal integrity studies. This algorithm allows the derivation of a rational approximation to the transfer matrix of a given linear structure starting from measured or simulated frequency responses. This paper addresses the convergence properties of a VF when the frequency samples are affected by noise. We show that small amounts of noise can seriously impair or destroy convergence. This is due to the presence of spurious poles that appear during the iterations. To overcome this problem we suggest a simple modification of the basic VF algorithm, based on the identification and removal of the spurious poles. Also, an incremental pole addition and relocation process is proposed in order to provide automatic order estimation even in the presence of significant noise. We denote the resulting algorithm as vector fitting with adding and skimming (VF-AS). A thorough validation of the VF-AS algorithm is presented using a Monte Carlo analysis on synthetic noisy frequency responses. The results show excellent convergence and significant improvements with respect to the basic VF iteration scheme. Finally, we apply the new VF-AS algorithm to measured scattering responses of interconnect structures and networks typical of high-speed digital systems

Revision, extension, and validation of Jordan's formula to calculate the surge impedance of vertical conductors

Abstract: Jordan's formula to calculate the surge impedance of vertical conductors is revised and extended to take into account systems with multiple conductors. Experimental data and the hybrid electromagnetic model are applied in order to validate the derived expressions. Additionally, Jordan's formula is successfully used in the representation of an actual tower as a multiconductor vertical system. The obtained results indicate the usefulness of the derived expressions if an engineering analysis of direct strikes over elevated strike objects is required

FDTD Simulation of a Horizontal Grounding Electrode and Modeling of its Equivalent Circuit

Abstract: Transient responses of a horizontal grounding electrode in three different arrangements of a current lead wire and a voltage reference wire are calculated using the finite-difference time-domain (FDTD) method for solving Maxwell's equations. The test arrangement does not significantly influence the transient response of the horizontal grounding electrode. The transient response calculated using the electromagnetic transients program (EMTP) for Sunde's equivalent circuit agrees reasonably well with the corresponding response calculated using the FDTD method, except for the initial rising portion of the voltage at the close end (to the excitation point) of the horizontal grounding electrode. The EMTP-calculated response for an equivalent circuit, modified to improve this discrepancy, agrees better with the corresponding FDTD-calculated response

Modeling of Transformer Windings Under Very Fast Transient Overvoltages

Abstract: To calculate the overvoltages in transformer windings under very fast transient overvoltages (VFTOs) generated by switching operations in gas-insulated substation (GIS), a single-input and multiple-output circuit model, which is based on a multiconductor transmission line (MTL) model, is presented in this paper. The procedure to determine the transfer function is deduced. Vector fitting and recursive convolution are used to calculate the time domain response. The resonant frequencies and the location of the resonance are determined by an analysis of the amplitude-frequency response characteristics. For validation, the calculated results are compared with the measurements on a transformer winding model, and the results are found to be satisfactory

Innovative test method for the shielding effectiveness measurement of conductive thin films in a wide frequency range

Abstract: This paper presents an innovative test procedure for the prediction of the shielding effectiveness of small sample materials, consisting of a dielectric substrate coated with thin conducting film, in a wide frequency range up to 8 GHz. The proposed technique overcomes the limitations of the ASTM D4935 test method concerning the upper operating frequency and the required minimum specimen dimensions. A new high-order equivalent circuit model of the test fixture is developed. A correction factor is applied to the measured insertion loss to eliminate both the resonance peak below cutoff appearing in the high-frequency range and the low-frequency errors due to the weak capacitive coupling between the flanges of the coaxial cell. The accurate prediction of the shielding effectiveness of the test material against a plane wave is then derived from the insertion loss measurements.

Correlation between maximum temperature increase and peak SAR with different average schemes and masses

Abstract: This paper investigates the correlation between maximum temperature increases and peak spatial-average specific absorption rates (SARs), calculated by different average schemes and masses. For evaluating the effect of mass on the correlation properly, a three-dimensional Green's function is presented. From our computational investigation, no best average mass for peak spatial-average SAR exist from the aspect of the correlation with maximum temperature increase. This is attributed to the frequency dependent penetration depth of EM waves. Maximum temperature increase in the head including the pinna is reasonably correlated with peak spatial-average SARs for most average schemes and masses considered in this paper. Maximum temperature increase in the head only (excluding the pinna) is reasonably correlated with peak 10-g SARs for the average schemes considered in this paper. The rationale for this result is explained using the Green's function. The point to be stressed here is that the slope correlating them is largely dependent on the average scheme and mass. Additionally, good agreement is observed in the slopes obtained by using two head models, which have been developed at Osaka University and Nagoya Institute of Technology. However, weak correlation is observed for the brain, which is caused by the difference of the positions where peak SAR and maximum temperature increase appear. The 95th percentile values of the slope correlating maximum temperature increases in the head or brain and peak spatial-average SAR are quantified for different average schemes and masses

FDTD analysis of plane wave superposition to simulate susceptibility tests in reverberation chambers

Abstract: The behavior of a device in a reverberation chamber can be analyzed as the same device irradiated by random plane waves. This work proposes an application of the finite difference time domain method to analyze the device by using a superposition of random plane waves, simulating the behavior of a reverberation chamber. The analysis of a transmission line compared with theoretical and experimental results in a reverberation chamber is reported

Relation between the amplitude probability distribution of an interfering signal and its impact on digital radio receivers

Abstract: New emission limit requirements are needed to protect digital communication systems from radiated interference. Traditionally, standard emission requirements have focused on protecting analog amplitude modulated radio services. However, developments in digital technology require emission limit requirements adapted to protect digital radio communication services. The amplitude probability distribution (APD) of the envelope or the quadrature components of an interfering signal has been shown to be related to the bit error probability of some digital radio receivers. However, a general description of the APD of an interfering signal and its impact on digital coherent radio receivers has not been presented. The aim of this paper is to clarify this relationship for a larger group of digital radio receivers. A method of incorporating the APD in conventional error expressions developed for digital coherent radio receivers in additive white Gaussian noise is presented. Furthermore, the relation between the maximum error probability for different digital modulation schemes and the APD is described, which allows definition of emission requirements on the APD

Multiple Slope Switching Waveform Approximation to Improve Conducted EMI Spectral Analysis of Power Converters

Abstract: An improved and simplified electromagnetic interference (EMI) modeling method based on multiple slope approximation of device-switching transitions for EMI analysis of power converters is presented. The traditional noise source modeling method, which uses single slope for rise and fall transition, is studied, and the criteria for reasonable modeling in the frequency range is analyzed. The turn-on and turn-off dynamics are investigated by dividing the nonlinear transitions into several stages based on an insulated gate bipolar transistor (IGBT) behavior circuit model. Real device-switching voltage and current waveforms are approximated by piece-wise linear lines and modeled by multiple dv/dt and di/dt slopes. The predicted EMI spectra suggest that high-frequency EMI noise is modeled with an acceptable accuracy. The proposed method was verified experimentally for a dc-dc buck converter

FDTD-derived correlation of maximum temperature increase and peak SAR in child and adult head models due to dipole antenna

Abstract: This paper investigates the correlation between the peak specific absorption rate (SAR) and the maximum temperature increase in head models of adults and children due to a dipole antenna. Much attention is paid to the effect of variation of electrical and thermal constants on the correlation for the child models, since these constants of child tissues are different from those of adult tissues. For investigating these correlations thoroughly, a total of 1400 situations are considered for the following six models: 3-year-old child, 7-year-old child, and adult models developed at the Nagoya Institute of Technology and the Osaka the University. The numerical results are analyzed on the basis of statistics. We find that the maximum temperature increases in the head can be estimated linearly in terms of peak SAR averaged over 1- or 10-g of tissue. In particular, no clear difference is observed between the adult and child models in terms of the slopes correlating the maximum temperature increase with the peak SAR. Also, the effect of electrical and thermal constants of tissue on these correlation is found to be marginal. Further, we discuss possible maximum temperature increases in the head and brain for SAR limits prescribed in safety guidelines. For the adult model developed at the Osaka Univ., these are found to be 0.26degC and 0.10degC at the SAR value of 1.6 W/kg for 1-g cubic tissue and 0.59degC and 0.21degC at the SAR value of 2.0 W/kg for 10-g cubic tissue. Similarly, for the 3-year-old child model at Osaka Univ., these are 0.23degC and 0.11degC for the value of 1-g SAR and 0.53degC and 0.20degC for the value of 10-g SAR

Inductor winding capacitance cancellation using mutual capacitance concept for noise reduction application

Abstract: In this paper, the properties of mutual capacitance between two capacitors are first discussed. It is found that the effects of mutual capacitance can be represented by two positive or negative capacitors across the two capacitors. These two equivalent capacitors can be used to cancel the parasitic capacitance of inductors. Because the mutual capacitance can be emulated using two small capacitors, the proposed method can easily be implemented in practical components. The prototypes are then built and the cancellation is verified using a network analyzer. Further EMI measurements in a practical power circuit prove that there is a significant improvement in the inductor's filtering performance.

Susceptibility of Personal Computer Systems to Fast Transient Electromagnetic Pulses

Abstract: In this paper, the susceptibility of personal computer systems (mainboard class vary from 8088 processor based system up to Pentium III system) to fast transient electromagnetic pulses (EMP) with double exponential pulse shapes [EMP, ultra wideband (UWB)] is determined. The influence of computer generation, random access memory (RAM)-values, program states, and pulse shapes, as well as the destruction thresholds of single personal computer (PC)-components [central processing unit (CPU), RAM, basic input/output system (BIOS), mainboard] have been investigated. The major result is that susceptibility increases significantly with each computer generation

Analysis of noise coupling from a power distribution network to signal traces in high-speed multilayer printed circuit boards

Abstract: As layout density increases in highly integrated multilayer printed circuit boards (PCBs), the noise that exists in the power distribution network (PDN) is increasingly coupled to the signal traces, and precise modeling to describe the coupling phenomenon becomes necessary. This paper presents a model to describe noise coupling between the power/ground planes and signal traces in multilayer systems. An analytical model for the coupling has been successfully derived, and the coupling mechanism was rigorously analyzed and clarified. Wave equations for a signal trace with power/ground noise were solved by imposing boundary conditions. Measurements in both the frequency and time domains have been conducted to confirm the validity of the proposed model.

Coupling reduction in enclosures and cavities using electromagnetic band gap structures

Abstract: The physical mechanism behind electromagnetic interference (EMI) is the coupling of energy between different primary and secondary sources of radiation and components within the package or chassis. This coupling can be either through conduction or radiation. However, regardless of the coupling mechanism, surface currents are needed to support the electromagnetic fields that eventually cause radiation, which in turn, constitute the EMI in the victim component. Minimizing these surface currents is considered a fundamental and critical step in minimizing EMI. In this work, we address novel strategies to confine surface currents. Unlike the traditional use of lossy materials and absorbers, which can be costly and can suffer from considerable disadvantages including mechanical and thermal reliability leading to limited life time, we consider the use of electromagnetic band gap (EBG) structures. These structures are inherently suited for surface current suppression. Their design is straightforward, and they are inexpensive to implement and do not suffer from the limitation of the previous methods used for the type of EMI suppression previously described. The effectiveness of the EBG as an EMI suppresser will be demonstrated using numerical simulations and measurements.

Statistical model of an undermoded reverberation chamber

Abstract: Weibull distribution is adopted to model the electric field component of a Reverberation Chamber (RC) Its first property is to include the asymptotic laws, such as Rayleigh and exponential, and its main advantage lies in the fact that the Weibull shape parameter enables a model of the departure from overmoded to undermoded RC regime Applications are given, such as an RC modal finite element modeling and a Monte Carlo simulation: they prove that the Weibull two-parameter distribution correctly models the quality factor influence Moreover, the relevance of the use of this extreme value distribution is illustrated

Validation of modal/MoM in shielding effectiveness studies of rectangular enclosures with apertures

Abstract: This paper discusses the validation of Modal/method of moments (MoM) including cases when the apertures are made as big as the wall of the enclosure (equivalent to having one side of the cavity open). The validation is done using field computations involving bodies of arbitrary shape (FEKO), a commercially available code. The results show that Modal/MoM predicts the results close to the analytical results of Robinson et al. Electron. Lett., 32 (17), 1996; Robinson et al., IEEE Trans. Electromagn. Compat., 40 (3), 240-247, 1998 for single-aperture cases and for most double-aperture cases. Also, for the cases of considering oblique incident plane waves, through validation, it has been found that Modal/MoM can predict the shielding effectiveness close to measured results for smaller angles and not for larger angles of incidence due to the edge effects. In this work, the shielding effectiveness is calculated at only one point, the center of the cavity assuming it to be the worst case. This work discovers the limitation of Modal/MoM for certain applications.

A closed-form expression for estimating radiated emissions from the power planes in a populated printed circuit board

Abstract: An expression for the maximum intensity of radiated emissions from a rectangular power bus structure has been derived based on an analytical cavity-resonator model. The effect of components mounted on the board is modeled by modifying the propagation constant of the waves within the power bus structure. The radiated field intensity is calculated using the equivalent magnetic current around the edges of the power bus structure together with the modified propagation constant. Measurements of a populated test board show that the derived closed-form expression estimates the level of the maximum radiation intensity with reasonable accuracy

Power line filter design for conducted electromagnetic interference using time-domain measurements

Abstract: A time-domain technique for the design of passive power line conducted electromagnetic interference (EMI) filters in the frequency range 150 kHz-30 MHz is described. A digital storage oscilloscope (DSO) with adequate sampling, storing and processing features is sufficient for the design using the proposed technique. Accordingly, Agilent's Infiniium Oscilloscope (Model 54810A) has been used. The signals from LISN are directly fed into the two channels of the DSO where they are added and subtracted to separate the CM and DM components, thereby eliminating the need for common-mode-differential mode (CM-DM) separator. These components are stored in the DSO. A specially designed filter design software (FDS), residing in the DSO, estimates the noise spectrum by computing the Bartlett and Welch periodograms. It also computes the filter component values. Thus, the sampling of the conducted noise, separation of CM and DM components, signal processing, and filter value computations are all done using one DSO. A spectrum analyzer is not required. Bartlett periodograms have been preferred over Welch periodograms due to low memory storage requirements of the former. The proposed technique has been applied to the design of power line filter for a switched mode power supply (SMPS), and satisfactory results have been obtained. The proposed measurement scheme is compact, economical, and convenient. All the details of this work are presented

Detection and Identification of Vehicles Based on Their Unintended Electromagnetic Emissions

Abstract: When running, vehicles with internal combustion engines radiate electromagnetic emissions that are characteristic of the vehicle. Emissions depend on the electronics, harness wiring, body type, and many other features. Since emissions are unique to each vehicle, these may be used for identification purposes. This paper investigates a procedure for detecting and identifying vehicles based on their RF emissions. Parameters like the average magnitude or standard deviation of magnitude within a frequency band were extracted from measured emission data. These parameters were used as inputs to an artificial neural network (ANN) that was trained to identify the vehicle that produced the emissions. The approach was tested using the emissions captured from a Toyota Tundra, a GM Cadillac, a Ford Windstar, and ambient noise. The ANN was able to classify the source of signals with 99% accuracy when using emissions that captured an ignition spark event

Fast transient analysis of incident field coupling to multiconductor transmission lines

Abstract: Due to the rapid surge in operating frequencies and complexity of modern electronic designs, accurate/fast electromagnetic compatibility/interference analysis is becoming mandatory. This paper presents a closed-form SPICE macromodel for fast transient analysis of lossy multiconductor transmission lines in the presence of incident electromagnetic fields. In the proposed algorithm, the equivalent sources due to incident field coupling have been formulated so as to take an advantage of the recently developed delay extraction based passive transmission line macromodels. Also, a method to incorporate frequency-dependent per-unit-length parameters is presented. The time-domain macromodel is in the form of ordinary differential equations and can be easily included in SPICE like simulators for transient analysis. The proposed algorithm while guaranteeing the stability of the simulation by employing passive transmission line macromodel, provides significant speed-up for the incident field coupling analysis of multiconductor transmission line networks, especially with large delay and low losses

On “Maximum Power Available to Stress Onto the Critical Component in the Equipment Under Test When Performing a Radiated Susceptibility Test in the Reverberation Chamber”

Abstract: We show, by theory and experiment, that the stress put onto the equipment under test (EUT) when performing a radiated susceptibility test in a reverberation chamber (RC) is not affected by either the directivity pattern or the receiving polarization pattern of the EUT. The stress put onto the EUT will differ from the stress measured by a reference antenna in the RC. We have developed distribution functions for this discrepancy.

Hybrid analytical modeling method for split power bus in multilayered package

Abstract: As multiple chips are being integrated into a single package with increased operating frequency, switching noise coupling on power buses has become an important design issue. To reduce the noise coupling, a split power bus structure has been generally used in package substrates having multilayered power and ground planes. Consequently, there is an increasing need for an efficient method to analyze a split power bus in a multilayered package. This paper introduces a hybrid analytical modeling method for characterizing a split power bus in a multilayered package. The proposed method uses a resonant cavity model combined with a segmentation method. Furthermore, a port assignment technique and an associated calculation method for the equivalent circuit model parameter of the split gap are proposed. The proposed port assignment technique and the analytical equation make it possible to analyze a split power bus, especially in a multilayered package. To verify the proposed method, multilayered test packages are fabricated and tested by means of frequency-domain measurements. In addition, an optimal power bus design method was successfully demonstrated for suppressing noise coupling between chips on a single package. Finally, the proposed method and optimal power bus design method was verified using a series of frequency-domain and time-domain measurements

On the Evaluation of Antenna-Mode Currents Along Transmission Lines

Abstract: In this paper, we derive an integral equation describing the antenna-mode currents along a two-wire transmission line (TL). We show that when the cross-sectional dimensions of the line are electrically small, the integral equation reduces to a pair of TL-like equations with equivalent line parameters (inductance and capacitance). The derived equations make it possible to compute the antenna-mode currents using any traditional TL coupling code with appropriate parameters. The derived equations are tested against numerical results obtained using numerical electromagnetics code (NEC), and reasonably good agreement is found