Search

The increasing number of electronic devices on board and the use of novel composite materials in the aerospace industry create a harsh electromagnetic environment that must be studied. In this article, a UAV demonstrator (DEMO-E3) with different test cases is evaluated through the low-level swept field test following a nested resonant chambers approach, which is framed under the high intensity radio frequency measurements. The aim is to analyze the difference in terms of the shielding effectiveness of the enclosure considering the different materials and apertures of each test sample. Some of the test cases had been previously measured independently, according to the IEC 61000-4-21 standard, while in this study, they are incorporated into the demonstrator and former results are used as a comparison. [ABSTRACT FROM AUTHOR]

The article investigates the shielding effectiveness (SE) of a metallic enclosure with a multilayer composite cover over a wide frequency range, from near-field magnetic shielding (1 Hz–1 MHz) to far-field electromagnetic shielding (4–14 GHz). Two enclosures are considered: a conductive enclosure made of aluminum and a magnetic enclosure made of steel. The multilayer composite is a trilayer combining a thin conductive layer of graphene and a thin magnetic layer of a Fe-Ni alloy on either side of a fiberglass plate. To determine the SE of these enclosures in both low-frequency and high-frequency approaches, two experimental setups and two numerical models are developed. The use of the composite cover, instead of the metallic one, gives a similar level of SE in the far-field and a higher specific SE (i.e., SE divided by the material density) in the near-field from 1 Hz to 2 kHz. Such quantitative analysis is the first step to designing practical enclosures entirely covered with composite panels to face electromagnetic compatibility (EMC) constraints in embedded systems. [ABSTRACT FROM AUTHOR]

This article presents the results of an experimental study of a structure with single modal reservation (MR). The decomposition of an ultrawideband (UWB) pulse in such a structure before and after failures has been demonstrated for the first time. For this case, authors used two bell-shaped pulses with a total duration of 0.15 and 1.5 ns. The frequency dependences of the transmission coefficient magnitude |S21| were measured for the manufactured prototype in the range from 10 MHz to 18 GHz. The results demonstrate that the structure before and after failures acts as a low-pass filter. To confirm the results of the experiment, its numerical simulation was carried out using two approaches: quasistatic and electrodynamic. In doing so, we took into account losses in conductors and dielectrics. To numerically estimate the criticality of the voltage waveforms obtained during the experiment at the output of the reserved circuit before and after failure, we calculated the N-norms. The simulation and experimental results in the time and frequency domains agree quite well. It was shown experimentally that after failures the maximum changes in the cutoff and the resonant frequencies are 45% and 19%, respectively. This suggests that after failures, the results may not coincide with the predicted ones, which must be taken into account when designing real structures with MR. It was found that in the time domain after failures, the maximum amplitudes of the decomposition pulses at the far-end of structure with a single MR change, and these changes depend on the duration of the UWB pulse at the input. This influence is explained by the length of the traces to SMA connectors. If the double delay in the trace is greater than the total pulse duration, then after failures, the amplitudes will not change, since the reflected pulses will not be superimposed on the main ones. However, as the length increases, the UWB pulse will be superimposed on the main ones and will change the maximum amplitude. This effect must be taken into account during design process as it can affect the interference immunity and functional safety of the device. This is shown in the analysis of N-norms. [ABSTRACT FROM AUTHOR]

In this article, we revised the commonly known engineering return stroke models for elevated objects, by taking into account the relativistic Doppler effect of the return stroke velocity shift. This revised model is applied to calculate the electromagnetic lightning field, struck by the Peissenberg tower using the finite difference time domain method in two-dimensions method. The simulation results are both compared with the results of the experimental measurements and with those obtained from the only two theoretical extending models existing in the literature that consider the presence of towers. Results show that the vertical lightning electric field is in perfect agreement with that measured experimentally, which means that this novel model was able to eliminate the nonphysical aspect of the transmitted current wave velocity from the tower top to the lightning channel observed in the hypothesis of the other authors and to reproduce in a more refined way the experimental measured electric field. The magnetic field behavior presents a concordance in the first peak and a slight difference in the tail waveform with that measured experimentally. These new formulations approximate the reality of the lightning radiation and, thus, allow to improve protection against its harmful effects. [ABSTRACT FROM AUTHOR]

Electromagnetic shielding is one of the most important branches of Electromagnetic Compatibility. Traditionally, metals were commonly used for shielding materials due to their high conductivity. Recently, however, increasing needs have emerged for lightweight, flexible, optical transparent, non-corrosive shielding materials to be used in flexible electronics, aerospace, and automotive manufacturing. For these reasons, carbon-based materials, such as graphene, have attracted increased attention for shielding applications. The main objective of this work is to evaluate ideal monolayer graphene as a shielding material for cylindrical configurations in the RF/microwave region. The numerical modeling of the involved structures is performed by the Method of Auxiliary Sources (MAS). Particularly, since the standard MAS suffers from numerical difficulties when applied in highly-conductive regions, a modified version of MAS is employed in which the graphene layer is replaced by an Impedance Matrix Boundary Condition (IMBC). The same condition is also applied for the case of a Few Layer Graphene (FLG) shield. The derived numerical results are found to be in excellent agreement with those obtained by FEM-based commercial software. [ABSTRACT FROM AUTHOR]

To introduce the interference aggregation effect into the emission-limit-setting model, aggregate interference power arising from randomly distributed disturbance sources is studied considering the near- to far-field propagation of radiated disturbance. It is assumed that point sources are uniformly distributed in a two-dimensional model and that the distance to the victim receiver ranges from the near-field region to the far-field region. A piecewise approximation is applied to the distance attenuation curve with a corner distance that indicates the border between the near and far fields. The mean value, standard deviation, and probability density function (PDF) of the decibel-scaled aggregate interference power are theoretically and numerically analyzed at various source densities. The results show that the shape of the PDF markedly changes as the source density increases because of the mixed contribution of disturbing sources both from the near and far fields. Accordingly, the variations in the mean value and standard deviation of the aggregate interference power are strongly dependent on the distance attenuation at which major interfering sources are found. When introducing the interference aggregation effect into the emission requirements, both the distance attenuation characteristics and the estimated source density in a real environment should be carefully considered. [ABSTRACT FROM AUTHOR]

In this article, time diversity is used as an electromagnetic resilience technique in a triple modular redundant (TMR) communication channel that is subjected to a multiharmonic electromagnetic disturbance under semireverberant environments. This study is carried out in light of new electromagnetic interference (EMI) condition monitoring definitions, which provide a better insight into the actual state of the system. An explanation of the different fault mechanisms based on the new definitions is provided for a time diverse TMR system with a two-out-of-three majority voter and is compared with the previously used EMI condition monitoring definitions. The new definitions provide a better understanding on how to interpret the results of an EMI detector or an EMI corrector by keeping in consideration the safety and availability aspects of system. [ABSTRACT FROM AUTHOR]

Using a new propagation measurement set-up, which produces a high number of data, enabling a proper statistical analysis, and resulting in very concise results, propagation measurements were performed and analyzed at 16 residential locations in The Netherlands in the frequency range from 1.8 to 28 MHz. In the whole frequency range the propagation loss appears to be higher than might be expected according the International Telecommunication Union ground-wave propagation model. Also typical characteristics of that model are not present, but instead the propagation shows a constant roll-off in dBs per decade, with a slope increasing with frequency. A regression curve could be established, and constants filled in. This statistical information may be used for building an accumulation model to lay a causality between source powers, source densities, and local man-made noise levels. [ABSTRACT FROM AUTHOR]

The determination of noise sources of radiated electromagnetic noise is the first task that needs to be addressed when an electromagnetic compatibility (EMC) problem appears. Broadband noise sources are more difficult to identify, particularly when similar switching frequencies are used by different sources. Four techniques for the fast determination of broadband electromagnetic noise sources in complex equipment are proposed. All the four techniques make use of one-port measurements conducted in near and far field in different time instants, avoiding unwanted effects of the near-field measurement equipment on the far-field distribution. Two techniques are based on modulation frequency analysis, a technique that was recently introduced in EMC. The remaining two techniques make use of the cross-correlation with the time-dependent high-frequency components in far field. Two of the four techniques require only low-frequency measurements in near field and are particularly suitable for high power equipment. The proposed techniques are validated by measurements. [ABSTRACT FROM AUTHOR]

The traditional finite-difference time-domain (FDTD) method is constrained by the Courant–Friedrich–Levy condition and suffers from the notorious staircase error in electromagnetic simulations. This article proposes a 3-D conformal locally one-dimensional FDTD (CLOD-FDTD) method to address the two issues for modeling perfectly electrical conducting (PEC) objects. By considering the partially filled cells, the proposed CLOD-FDTD method can significantly improve the accuracy compared with the traditional locally one-dimensional FDTD (LOD-FDTD) method and the FDTD method. At the same time, the proposed method preserves unconditional stability, which is analyzed and numerically validated using the von Neumann method. Significant gains in central processing unit time are achieved by using large time steps without sacrificing accuracy. Two numerical examples, including a PEC cylinder and a missile, are used to verify its accuracy and efficiency with different meshes and time steps. It can be found from these examples that the CLOD-FDTD method shows better accuracy and can improve the efficiency compared with those of the traditional FDTD method and the traditional LOD-FDTD method. [ABSTRACT FROM AUTHOR]

Near-field scanning is an attractive method to diagnose conducted and radiated emission issues at board or circuit level. However, the long measurement time to scan a dense electronic board at numerous frequencies is a major drawback that limits its growth in industry. To overcome this problem, methods to accelerate the measurement, such as the sequential spatial adaptive sampling algorithm, must be found. This method was developed to speed up a near-field scans measured in frequency domain at only one frequency. The proposed article capitalizes on this method to extend its principle and demonstrate its effectiveness for near-field scans measured at multiple frequencies. Several measurement strategies and frequency segmentation approaches are compared. A definition of the best strategy and approach to allow a time reduction factor of almost one order magnitude compared to the full sampling measurement has been proposed. [ABSTRACT FROM AUTHOR]

Series-connected insulated gate bipolar transistors (IGBTs) are vastly adopted in high-voltage/power converters. It has been shown in prior researches that shaping the switching element transient voltage to an “S”-shape profile decreases EMI considerably. This article proposes a series-stacked IGBT switch (SSIS) with pulse shaping capability. According to this feature, the voltage of the SSIS has a Gaussian profile in the rising time interval. The method works based on the specific delayed operation of the series-connected IGBTs. In this approach, all IGBTs are turned on/off as fast as possible. Hence, the EMI reduction is not obtained at the expense of the switching power loss increment. Moreover, the power loss relevant to the delayed operation of the IGBTs transfers to the main dc bus. Thus, the overall efficiency is not affected by the proposed approach. In order to validate the proposed approach, PSPICE simulations as well as the experimental results are provided. [ABSTRACT FROM AUTHOR]

To identify and improve the electromagnetic compatibility of a global navigation satellite system (GNSS) receiver under a complex electromagnetic environment, the blocking effects of single-frequency and out-of-band dual-frequency electromagnetic radiation (EMR) on a GNSS receiver were experimentally analyzed. This study is the first to investigate second-order intermodulation second-order intermodulation low-frequency blocking (SILB) interference which was newly discovered in our tests. The mechanism of the SILB effect was analyzed, and two key parameters were identified. The SILB interference factor and the relative value of the low-frequency interference level were introduced to establish a model predicting SILB effects. The method of determining the parameters, the modeling process, and the results are discussed in this article on the basis of both theoretical derivations and experimental measurements. A GNSS receiver was used as the equipment under test to verify the model. Notably, the results demonstrated that the threshold for SILB was approximately 30 dB lower than that for out-of-band single-frequency interference. The model proposed in this article accurately evaluated and predicted the SILB interference. [ABSTRACT FROM AUTHOR]

Since many electromagnetic compatibility tests are resourcelimited, it is important to quantify the uncertainties of instruments beforehand. One of the common instruments is the trigger pulse generator with self-breakdown switches. Due to the abrupt changing caused by self-breakdown switches, stochastic methods based on the generalized polynomial chaos suffer from Gibbs-type phenomena and become erroneous around abrupt transition point. This article proposes an effective technique based on the Haar wavelets for quantifying the time delay of self-breakdown switches in stochastic simulations. Wiener–Haar wavelet expansion method is suitable for dealing with abrupt-changing problems and is applied to the nodal-analysis-based circuit model. The stochastic circuit model is expanded to an augmented model with deterministic coefficients by exploiting wavelets’ orthogonality. Furthermore, the distribution of time delay is represented as the mean value of a Heaviside function, which is implemented by an auxiliary circuit in the model. The statistical mean can be directly obtained from the 0th coefficient of Wiener–Haar expansion. A case study of a trigger generator for electromagnetic pulse generators is provided to validate the effectiveness of the proposed method. It is shown that, compared with Monte Carlo methods, Wiener–Haar representation provides robust results with less computational time and a faster convergence rate. [ABSTRACT FROM AUTHOR]

For the functionality of the modern electric and electronic devices, high current is needed. However, this can produce a very high magnetic field in cables especially for low frequency ranges to 400 kHz according to IEC TS 42764-1, which can infringe the legal limits and the thresholds for health protection. Generally, to evaluate the influence of the radiated magnetic field, measurements and comparison with the related standards are needed. To check the magnetic field, full wave simulation can be applied. However, such simulations can be extremely time-consuming. Therefore, alternative calculation methods, which can predict magnetic fields reliably in short time, are needed. This article presents a fast calculation approach based on the superposition of the magnetic field radiated by a conductor and the equivalent model of the ground plane. This equivalent model consists of different regions, where the return currents flow.These currents are calculated as a function depending on the total current, the material of the ground plane and the frequency.The results of the fast calculation approach are then validated by comparing them to the results of the full wave simulation and measurement. [ABSTRACT FROM AUTHOR]

In 2015, the energy measurement of some static electricity meters was found to be sensitive to specific conducted electromagnetic disturbances with very fast current changes caused by highly nonlinear loads, leading to meter errors up to several hundred percent. This article describes new results on the electromagnetic compatibility (EMC) of 16 different meters from all over Europe when exposed to real-world disturbance signals. Those test signals were obtained from household appliances and onsite measurements at metered supply points all over Europe. The results show that also the interference signals recorded onsite can cause measurement errors as large as several hundred percent, even for meters that pass the present EMC standards. This unambiguously demonstrates that the present immunity testing standards do not cover the most disturbing conducted interference occurring in present daily-life situations due to the increased use of nonlinear electronics. Furthermore, to enable the adoption of potential new test waveforms in future standards for electricity meter testing, artificial test waveforms were constructed based on real-world waveforms using a piece-wise linear model. These artificial test waveforms were demonstrated to cause meter errors similar to those caused by the original real-life waveforms they are representing, showing that they are suitable candidates for use in improved standardization of electricity meter testing. [ABSTRACT FROM AUTHOR]

Rising voltages and wide bandgap semiconductors represent the main cause for rising electomagnetic interference (EMI) emissions of dc–dc converters in electric vehicles. Conventional passive filters are the limiting factor for the improvement of the power density and conventional active EMI filters are quite complex. This article presents a method in order to compensate the EMI generated by a dc–dc converter using a simple half-bridge gate-driver IC. The compensation signal is synchronized to the converter's switching events and injected through two capacitors at the converter's input nodes. Unlike analog active EMI filters, this method is able to compensate time delays of the filter's hardware components. This article presents an approach to describe such a compensation system analytically. Therefore, bandwidth and attenuation are determined due to the synchronization error and pulse amplitude. The presented prototype system and the analytical prediction are validated by measurements at the stationary operation of the converter in a CISPR 25 test setup. Finally, the performance of the method during dynamic operation of the converter is evaluated to demonstrate the high EMI suppression effectiveness of pulsed compensation. [ABSTRACT FROM AUTHOR]

In this article, a method for solving cable layout optimization problems in electronic systems based on ensemble learning (EL) and improved differential evolution (DE) algorithm is proposed. Using this method, we produced two cable layout schemes with the considerations of the electromagnetic compatibility performance and the total length of cables. First, several different individual machine learning (ML) models for all output variables were established. On this basis, we established EL models with better performance than previous individual ML models. Then, aiming at the optimization problem presented in this article, an improved DE algorithm was proposed. On this basis, a method for solving cable layout optimization problems in electronic systems based on EL and the improved DE algorithm was proposed. Finally, the effectiveness of the proposed method was verified by two examples of electronic system cable layout optimization with different routing modes. Each example problem was solved using four different methods. The results indicate that the method proposed here outperformed existing methods. [ABSTRACT FROM AUTHOR]

The received signal of the electronic equipment often depends on its surrounding multidimensional dynamic electromagnetic environment (MDEE) featured with large airspace, high field strength and wide frequency band. This brings great challenges to predict the electromagnetic compatibility (EMC) of the electronic equipment dynamically. As an extension to the conventional equivalent construction (EC) process for the static single-source electromagnetic environment, based on the response of an antenna port, a novel EC method for the dynamical multi-source heterogeneous electromagnetic environment is proposed in this article. By applying this EC method to a radar system under a practical dynamic working scene, an innovative electromagnetic sensitivity threshold test method is carried out in the laboratory. The experimental results show that the theoretically predicted value is in good agreement with the measurement, where the error is less than 1dB. With the methods proposed in this article, the dynamic analysis and prediction of EMC in MDEE can be carried out with the consideration of the characteristics of the electronic equipment, so that the electromagnetic environment adaptability of the electronic equipment can be readily improved. [ABSTRACT FROM AUTHOR]

Lumped-element grids provide an attractive option for wave propagation control in electromagnetic compatibility (EMC) engineering. This article investigates the peak shielding effectiveness (SE) of a diode grid used for protection of enclosures with apertures against high-intensity radiation fields (HIRFs). The nonlinearly loaded aperture is investigated with an efficient hybrid field-circuit simulation approach. Numerical experiments show that design aspects, e.g., aperture and enclosure size, grid density, impedance characteristic of lumped loads, play an important role in the field transmission through a diode grid which is nonlinear and time-variant. With a physics-based analysis of the interaction between the grid and the enclosure-backed aperture, nonlinear shielding techniques are identified that allow a control of the peak SE between 0 and 26 dB in novel ways. For the first time, the peak SE curve of a diode grid is demonstrated with four different field intensity dependencies, i.e., intensity low-pass, intensity high-pass, intensity bandpass, and intensity band-stop selectivities from tens V/m to hundreds of V/m. By considering design aspects into a two-step optimization procedure, practical guidelines are provided for the nonlinear shielding implementation. [ABSTRACT FROM AUTHOR]

A resonant cavity undergoes three distinct behaviors with increasing frequency: 1) fundamental modes, localized in frequency with well defined modal distribution; 2) undermoded region, where modes are still separated, but are sufficiently perturbed by small imperfections that their spectral positions (and distributions) are statistical in nature; and 3) overmoded region, where modes overlap, field distributions follow stochastic distributions, and the slot acts as if in free space. Understanding the penetration through slots in the overmoded region is of great interest, and is the focus of this article. Since full-wave solvers may not be able to provide a timely answer for very high frequencies due to a lack of memory and/or computation resources, we develop bounding methods to estimate worst-case average and maximum fields within the cavity. After discussing the bounding formulation, we compare its results to full-wave simulations at the first, second, and third resonance supported by the slot in the case of a cylindrical cavity. Note that the bounding formulation indicates that results are nearly independent of cavity shape: only the cavity volume, frequency, and cavity quality factor affect the overmoded region, making this formulation a powerful tool to assess electromagnetic interference and electromagnetic compatibility effects within cavities. [ABSTRACT FROM AUTHOR]

Dealing with lightning performance computation, researchers usually consider only negative downward first return strokes and the relevant channel-base peak current distribution. The aim of this article is to account for the lightning flash mechanism, which means to include also downward negative subsequent strokes and downward positive strokes, taking into account available distributions of the number of strokes per flash (i.e., the flash multiplicity) and of the distance among the impact points of the strokes within the same flash (i.e., the channel terminations distance). In this regard, to the best of the authors’ knowledge, the present study is the first one taking into account the multiple ground channel terminations in the lightning performance assessment. The obtained results show that both the negative subsequent strokes and multiple channel termination determine a significant increase in the estimated number of flashovers per year, and they need to be considered in the lightning performance assessment. On the other hand, considering positive downward strokes, a less remarkable increase in the estimated number of flashovers per year is observed. [ABSTRACT FROM AUTHOR]

Automobiles are incorporating a vast number of automated electronic subsystems that control critical car functionalities related to safety, performance, and driving assistance. Electromagnetic compatibility is safeguarded by manufacturers but at the same time, these electronics offer a means of susceptibility to directed electromagnetic energy launched by law enforcement units aiming at controlling a car at a distance. In this article, we present the results of an experiments campaign evaluating the vulnerability of a car engine control and selected parts to intentional electromagnetic interference. Frequency bands of increased susceptibility are identified in order to minimize the impinging pulsed field's power, duty cycle, and number of pulses. The effect of car body electromagnetic attenuation is assessed and guidelines are given regarding the safety of passengers from both radiation and unexpected car behavior. [ABSTRACT FROM AUTHOR]

The switching operations of circuit breakers and disconnectors in substations can generate very fast transients, including transient earth voltage rise and intense electromagnetic radiation, causing severe disturbance of on-site electronic devices in substations and seriously affecting the development of smart power equipment. The power supply of an on-site electronic device provides a path along which the disturbance couples with the device. In this article, we investigated the coupling mechanism and measures to suppress this disturbance. We found that, for most on-site electronic devices, their power supply includes a power line that connects the exterior and interior of the shielding box, greatly reducing the shielding effectiveness and inducing disturbance from the outside to the inside. This article proposes a shielding–crossing isolation transformer as the power supply of which the primary winding is outside and the secondary winding is inside of the shielding box, without a power line across the shielding box. This arrangement proved to deliver the high performance in terms of eliminating disturbance from the power supply. This article provides an understanding of the mechanism according to which the electromagnetic disturbance couples through the power supply. A method to determine the electromagnetic compatibility of on-site electronic devices in a substation is also proposed. [ABSTRACT FROM AUTHOR]

In this article, the analysis of a reaction wheel's static and low-frequency (LF) magnetic fields is carried out. The key parameters that affect the spectral variations of the magnetic field emissions are identified and a sensitivity analysis is conducted in order to analyze the impact of these parameters to the field spectrum. Moreover, a methodology for modeling the magnetic signature of the reaction wheel's rotor for purposes of magnetic cleanliness is presented. The static near-field of the rotor is employed to estimate the associated model parameters that may reproduce its magnetic signature. Furthermore, the determined parameters are used to predict the LF magnetic spectrum in the operating mode of the wheel. This analysis illustrates the significance of the targeted accuracy during the manufacturing process of this type of equipment and provides a deep understanding on development of methods to satisfy demanding magnetic cleanliness requirements in space missions. [ABSTRACT FROM AUTHOR]

Metamaterial absorbers have been introduced as custom-designed solutions for mitigating radiated emissions from a system shield box. In this article, the analysis of these system enclosures is generalized by using a cavity analysis approach. Inspecting surface current, frequency, and quality factor of the resonant cavity modes of a shield box with metamaterial lining provides insight into evaluating and quantifying the efficacy of an absorber solution. The increased radiated emission from an enclosed system is traced back to the potential excitation of resonant cavity modes. The cavity modes can be excited when common mode signals are present at proper locations. In a generic high-speed differential signaling system, common mode signals are shown to be created as a result of differential line phase mismatches and demonstrated to yield strong spectral components at twice the harmonics of Nyquist frequency. A second design approach is introduced herein that involves finding the equivalent complex permittivity and permeability, i.e., an equivalent bulk material characteristic for the metamaterial absorber. This approach expedites the design of metamaterial absorbers and evaluation of their effectiveness for emission reduction from few hours to few minutes. [ABSTRACT FROM AUTHOR]

Control schemes applying sinusoidal pulsewidth (sPWM) have been widely employed in power conversion solutions. With the development of the future smart grid, more capabilities of the converters are required introducing additional electromagnetic interference (EMI) control measures. In this article, a MATLAB controllable sPWM generator has been developed to optimize electromagnetic compatibility. The field-programmable gate array running at 100 MHz is capable of producing simultaneous and synchronous control signals for 16 power electronic switches. Six flexible control parameters have been implemented, which allow the controller to be tuned to a large number of applications and investigate several EMI mitigation techniques and investigate the disturbance dependence on operational parameters. As an example, the detrimental dead time effect is shown, with a variation in emissions of 10–20 dB in the frequency range of 50 kHz to 50 MHz. Highest experimentally tested switching frequencies have been recorded at 2 MHz with resulting sinusoidal waveforms from 50 Hz to 250 kHz. [ABSTRACT FROM AUTHOR]

This article deals with an original equalization method of 3-D electromagnetic (EM) cavity resonance by using bandpass negative group delay (NGD) function. Based on the equivalent circuit, the S-matrix model of the equalized EM cavity is introduced. The design equations of the NGD function are established in function of the cavity physical parameters. The feasibility of the equalization method is validated with a 42×28×3.8 cm rectangular cavity containing two communicating monopole antennas. By considering the TE110-mode, a significant equalization is realized with improvement of transmission coefficient flatness from 4 dB to less than 0.3 dB. In addition to the magnitude, the NGD equalization method enables to outstandingly reduce spikes of 3-D EM cavity group delay. With the proof of concept, the GD is reduced from more than 4 to 1 ns. [ABSTRACT FROM AUTHOR]

The method of auxiliary sources (MAS) is an established technique for the numerical solution of electromagnetic shielding and scattering problems exhibiting an increasing interest for the simulation of various electromagnetic compatibility (EMC) applications. In previous works, it was shown that for the problem of transverse magnetic illumination of a perfect electric conducting cylinder by an electric current filament, it is possible for large numbers N of auxiliary sources that the MAS currents diverge and oscillate, while the generated MAS field converges to the exact solution. In this article, we further analyze the convergence issues and oscillations encountered in the MAS by considering the transverse electric case due to excitation by a magnetic current filament. We demonstrate analytically that the convergence/divergence phenomena of the currents and fields also occur in this problem and then study the nature of this divergence in detail. In particular, we prove a large-N asymptotic formula for the divergent MAS currents, which captures accurately the important characteristics of the associated inherent oscillations. Numerical results for noncircular shapes are also presented. The discussed effects must be carefully taken into account in EMC simulations pertaining to cylindrical conductors. [ABSTRACT FROM AUTHOR]

The explosive growth of electronic devices brings a soaring demand for rapid electromagnetic compatibility (EMC) diagnosis. However, there is a significant learning curve for the electrical engineers to apply EMC knowledge. In this article, an efficient EMC diagnosis and management methodology was proposed, which provided a fast way for EMC analysis in seconds other than traditional simulation or calculation. The approach organized the EMC knowledges as knowledge graph composed by the interference/sensitive units, and mathematical set rules. The optimized graph structure is in form of rule, maxterm, basic unit, and entity layers. Based on the condensed relationships, it achieved high searching efficiency and graph expansibility. To facilitate the information retrieval from the knowledge graph, the interference/sensitive units and related parameters were acquired from interactive sessions, in which long short-term memory method was used to extract entities. The EMC specialized corpora were fed in training to enhance the accuracy of inference. Finally, the EMC diagnosis and management reports were automatically generated by knowledge graph searching application. The proposed method improved the calculation efficiency by three times. The storage of relationships and attributes of nodes was reduced by 76% and 60.7%. The identification accuracy was enhanced from 77.7% to 99.5%. The presented method is practically useful for EMC design in crosstalk analysis, radiated, and conducted interference diagnoses. [ABSTRACT FROM AUTHOR]

The aim of this article is to describe the design, realization, and characterization of a compact, broadband, and calculable electromagnetic field source. The source has been extensively used as a traveling reference radiator in proficiency tests of radiated emission measurements. The result of its characterization has been validated by more than 500 measurements over the frequency range from 50 to 6000 MHz in semianechoic (3 and 10 m) and fully anechoic (3 m) chambers. The use of the source as a reference radiator for emission measurements could be extended to other testing facilities, such as transverse electromagnetic waveguides and reverberation chambers. [ABSTRACT FROM AUTHOR]

This article proposes and analyzes two possible methods to compensate the raw near-field data obtained with an array of near-field probes. The first method is based on the spatial compensation procedure for a single probe and is modified toward an array of probes. The second method is to use standard spectral (plane wave) single-probe compensation. To use the latter, guidelines on how to design an array and modify the overall measurement procedure such that mutual coupling and edge effects have less influence are given. The different methods are tested in simulation and compared with the performance of compensation on a single probe. It is shown that the standard spectral single-probe compensation, in combination with proper array design, will result in an error as low as the same compensation technique used on a single probe. It is also shown that the spatial compensation improves the results in comparison with regular calibration. However, the error is not low enough to be used for postprocessing due to ill-conditioning. This article shows the path to much needed, fast, and accurate near-field measurements. [ABSTRACT FROM AUTHOR]

Distributed vehicular control systems are responsible for safety-critical applications, depending on communication protocols. In this context, the FlexRay protocol is frequently applied for electronic control unit interconnection in critical applications. Thus, it must be tested in different fault scenarios to verify if the protocol could comply with hard timing constraints. Typical faults that have been studied are electrical fast transients, in which power switching systems can generate transients that degrade in-vehicle communication. Recent efforts focus on the specification of test methods for electromagnetic compatibility in communication transceivers, but without considering the negative impact on critical control system messages and its periodicity. This work presents a contribution by exploring the IEC 62228-3:2019 standard to guide the application of a test method with a specific test board to evaluate the impact of these faults on the control law performance of critical automotive control systems based on FlexRay protocol. The results show that during the test scenarios using the fault injection method, the transients cause performance degradation peaks between 2.9 and 94.5  $\mu$ s, much higher compared to a typical FlexRay delay. The results emphasize that critical control systems must be stressed with consistent tests to map fault behaviors, observing the operation limit under faults. [ABSTRACT FROM AUTHOR]

Presents the 2020 subject/author index for this publication. [ABSTRACT FROM AUTHOR]

In this article, we examine the coupling into an electrically short azimuthal slot on a cylindrical cavity operating at fundamental cavity modal frequencies. We first develop a matched bound formulation through which we can gather information for maximum achievable levels of interior cavity fields. Actual field levels are below this matched bound; therefore, we also develop an unmatched formulation for frequencies below the slot resonance to achieve a better insight on the physics of this coupling. Good agreement is observed between the unmatched formulation, full-wave simulations, and experimental data, providing a validation of our analytical models. We then extend the unmatched formulation to treat an array of slots, found again in good agreement with full-wave simulations. These analytical models can be used to investigate ways to mitigate electromagnetic interference and electromagnetic compatibility effects within cavities. [ABSTRACT FROM AUTHOR]

In wired signal transmission, conversion between the differential and common modes deteriorates the quality of the transmitted signal and also causes electromagnetic compatibility problems in the environment. Therefore, the transmission-line components are requested to be tested on their conversion loss characteristics, such as the longitudinal conversion loss (LCL), transverse conversion loss (TCL), and mixed-mode S-parameters. Theoretical investigations are carried out to analyze the mode conversion of a differential one-port device in order to express the conversion loss parameters in terms of the modal impedances of the device. Consequently, the mutual relationships among the parameters are derived using the modal impedances. In addition, a new LCL measurement method is proposed that can accurately determine LCL values of a device under test by using a vector network analyzer instead of a traditional balun-transformer measuring instrument. Furthermore, it is found that the ratio of the TCL to LCL is not constant but varies with device characteristics. Therefore, a new definition of the TCL is proposed in place of the conventional one. The validity of these theoretical results is confirmed through SPICE simulation and measurements. [ABSTRACT FROM AUTHOR]

This article presents a complete framework able to characterize the performances in both frequency and time domains of “vibrating intrinsic reverberation chambers” made of a metallized tent of shape continuously changing under the action of the stirring process. In the frequency domain, the analysis is based on a method proposed recently in order to assess from which frequency the chamber can be “well-stirred.” The method uses $S_{11}$ measurements of the emitting antenna in only one position of the VIRC for different stirring conditions, here at different instants. The performances of the VIRC are shown to be similar to the ones obtained in a “classical” parallelepipedic RC of similar volume. In the time domain, a method is proposed in order to measure the decorrelation time defined as the minimum interval of time to wait in order to collect two successive independent samples and to detect any periodical repetition of the stirring process. This time-domain analysis emphasizes that the number of collectable samples is proportional in a VIRC to the measurement time. The use of a VIRC could therefore contribute to severely decrease the uncertainty budget of some RC measurements such as antenna efficiency measurements or over-the-air testing of wireless devices. [ABSTRACT FROM AUTHOR]

In the article, the electromagnetic time reversal technique (EMTR) is studied in the electromagnetic compatibility context. The main issue addressed by this approach is to deal with electromagnetic (EM) radiating source identification. This article is intended to provide a time-domain (TD) study of EMTR in the near field (NF) and prove its efficiency in characterizing transient disturbances in power electronics. The reconstruction of EM emissions is based on two stages. First, the modeling process relies on the use of TD analytical expressions. Second, signal processing is referring to the time reversal technique, which defines an inverse problem resolution. The method proposes to identify a set of equivalent dipoles. The validation is carried out experimentally using a TD measurement bench. The main purposes of this method is to extract the dipoles locations, moments, and orientation. The magnetic field maps calculated at each time step using obtained equivalent sources are compared with measured distributions. Adequate agreement is achieved, which confirms the efficiency of the proposed method. In addition, for validation purposes, the equivalent model is compared with that obtained by a frequency-domain (FD) method based on the standard genetic algorithms. Unlike FD, TD investigations allow characterizing transient disturbances in power electronic systems that emit strong EM interferences, by finding a sufficient equivalent model valid on a wide frequency band at once. [ABSTRACT FROM AUTHOR]

This article presents a global methodology to test components (equipment) on table test bench with representative interferences found on vehicle simulation in case of wideband modulated pulse interferences. The proposed method consists, first, of using an electromagnetic three-dimensional simulation model of the vehicle already validated to quickly determine time-domain waveforms of the common-mode current at any load connected at the end of a copper wire located inside the vehicle under wideband modulated pulse interferences. The second step of the method consists of showing that representative interference waveforms obtained by simulation can be reinjected into a component under test using conducted injection means usually used for electromagnetic compatibility tests in automotive industry in order to cover vehicle tests in case of Wideband/Mesoband modulated pulse interferences. [ABSTRACT FROM AUTHOR]

This article proposes an electromagnetic compatibility improved bandgap voltage reference with a low current consumption of only 3.5 μA in an automotive environment with a wide temperature range from –40 °C to 160 °C and a high electromagnetic interference (EMI) robustness. The proposed reference is based on the well-known Brokaw bandgap with only five bipolar transistors in the bandgap core including collector current leakage compensation. We analyzed parasitic effects in the bandgap core such as the influence of parasitic capacitances between the substrate and the collectors of these bipolar transistors as well as the impact of the operational amplifier. We made recommendations on how to improve the bandgap EMI robustness. Simulation results were compared with measurements on a test chip. The measurement results showed excellent EMI robustness. [ABSTRACT FROM AUTHOR]

This letter presents an equation-based solution for the analysis of coupled nonuniform transmission lines (CNUTLs) in the frequency domain. The proposed methodology, which is based on state-transition matrix, models the Telegrapher's equations in form of linear position varying (LPV) system. Solving these equations with the Peano-Baker series (PBSs) provides the sought for closed-form far-end/near-end voltages and currents in the CNUTLs. Unlike the previous methods, due to the unique advantages of PBSs, such as versatility, performing with low-order terms, and subsequently, the high convergence rate, the proposed method is very fast and reliable. In order to validate the method, two practical CNUTLs of relevance in electromagnetic compatibility applications, namely, lossy/lossless exponentially and linearly tapered microstrips, are analyzed. Simulation results show that the proposed method is very accurate and fast in comparison to traditional methods. [ABSTRACT FROM AUTHOR]

In this article, we apply the broadband Green's function for fast full-wave simulations of the radiated emissions from the printed circuit boards (PCBs) of irregular shape. Changes were made on the previous version that improve the computational efficiency and accuracies of the solutions. The improvements include imaginary wavenumber extractions for the acceleration of convergence of modal expansions without the need of high-order quadrature, and the fast-exact normalization of modes. Results of the radiated fields are illustrated over a broad frequency range up to 10 GHz and for irregular shaped PCB up to 4 in in sizes. The results are in good agreement with the method of moment for both the modal solutions and the radiated emissions. The results are shown to be more accurate than the previous version of broadband Green's functions with low wavenumber extractions. The significant computational efficiency makes this technique useful for electronic design automation to electromagnetic interference/electromagnetic compatibility applications. [ABSTRACT FROM AUTHOR]

A constant electromagnetic compatibility issue in the majority of space missions is the accurate EMI source identification and modeling. This is necessary in order to provide electromagnetic (EM) cleanliness in a specific area inside or outside the spacecraft, where sensitive measurement equipment is placed. Authors in previous work have presented a stochastic process capable to accurately predict the EM signature of a device both for transient and steady-state emissions. In this article, a supplementary methodology is proposed, using the models from the previously established process, to achieve electromagnetic cleanliness. Authors claim that EM cleanliness is possible to be achieved inside or outside a specific area of the spacecraft structure with proper equipment ordinance and if necessary the aid of an additional auxiliary source. The proposed methodology is using a heuristic approach to find the optimum positions of the available equipment. The equipment when placed at these positions presents a minimum total electromagnetic field at a specific point or region. Moreover, if necessary, the total field can be further minimized with the addition of an auxiliary source. [ABSTRACT FROM AUTHOR]

This article proposes a new approach to background noise (BN) cancellation for low-frequency electromagnetic compatibility (EMC) emission testing between 30 Hz and 10 kHz. The method proposed in this article is based on the streaming and recording of oscilloscope data in a continuous period without interruption and without losing phase information. In the proposed method, the continuous and consecutive stream of the oscilloscope data contains two adjacent data segments inside. The first data segment consists of the equipment under test (EUT) and BN information together, whereas the second segment contains only the BN because the EUT is switched off in the middle of the continuous data stream. After gathering all the oscilloscope data, the BN that exists in the first segment is precisely estimated by means of the BN information, which exits in the second segment. This estimation is easily attainable as the phase difference is accurately known between any two points in the first and second segments. Afterward, the simple subtraction of the estimated BN data from the actual combined EUT and BN data yields the EUT time-domain data. The proposed method assumes that the spectral content of the BN is stable during the entire streaming process, which may typically last for a range of 10–20 s. Ultimately, the effective performance of the method for the extraction of the EUT signal from the BN is theoretically and experimentally demonstrated with an average deviation of less than 0.6 dB for the low-frequency emission EMC testing. [ABSTRACT FROM AUTHOR]

In this article, we use Newton's method and the nonlinear least squares method to solve a nonlinear problem in electromagnetic compatibility. Both techniques provide a way to identify the temporal profile of a voltage source that would produce a target voltage over a given time interval at a point of the transmission line network presenting nonlinear components. After comparing the results of a test problem, the most efficient method is considered to identify the temporal source in order to bring a software correction to a nonlinear faulty lossy transmission line network. The software correction process may cancel any unintentional perturbations produced by one or more faults regardless of their type and location. [ABSTRACT FROM AUTHOR]

In a multimodule system, an increase in the number of radiating optical modules will increase the electromagnetic emissions. This article investigates the scaled tendency of the emissions in a router system loaded with hundreds of optical modules. An artificial router mimicking the real system was built to investigate this tendency. A patch antenna array mimics the radiation of the optical modules. It can be excited in in-phase and random-phase configurations. The measurement data verifies the theoretical analysis and the prediction from a statistical method without performing hundreds of different experiments on a real router. Assuming that all radiators are radiating at the same frequency and have similar radiation pattern with random phases, the average of the maximal directivity of the system will saturate if the number of radiators (N) is larger than 14. Furthermore, the average of the maximal electric field radiated will increase following a 10 log10 N (dB) tendency. [ABSTRACT FROM AUTHOR]

The use of a vertically oriented rod antenna is requested by several standards for the measurement of radiated emissions below 30 MHz both from civil and military equipment. In all the cases, the measurements are performed with the antenna at short electrical distances from the equipment under test. The measurement results depend on the geometrical and electrical parameters of the setup in a not negligible and complex way. For this reason, during the years technical committees have tried to define a setup with boundary conditions able to provide the same measurement results whenever repeated. To that end, different bonding solutions for the counterpoise of the rod antenna have been proposed, obtaining different advantages and drawbacks. In this framework, in this article the authors describe the results of numerical and experimental analysis activities performed on the spatial distribution of the electric field under measurement in the proposed measurement setup. The activities have been done in order to define the optimal operative conditions that allow to obtain measurement results providing a faithful representation of the disturbance field generated by the equipment under test in undisturbed conditions, i.e., the field under measurement. Experimental activities have been performed with an innovative rod antenna with an integrated receiver that can also be operated in a completely isolated mode by using an optical fiber interconnection for its remote control. [ABSTRACT FROM AUTHOR]