EMC Applications Research Articles

Wideband Noncontact Voltage Measurement for EMC Applications: Design and Implementation

A methodology of amplitude and phase compensation for non-contact voltage measurements, which can be applied to wideband signal and noise observation in the EMC application, is presented. The non-contact techniques are based on a small amount of coupling capacitance between probe electrode and cable conductor where the observed signal is induced. In this case, a main technical issue to be overcome is the amplitude and phase error introduced by stray capacitance of the internal circuit, which needs to be resolved for application of the wideband EMC measurements. Herein, a design and implementation of phase compensation with inverting OpA configuration are discussed. Moreover, by introducing a system calibration with numerical process, validity for recovering the frequency response at 100 Hz ~ 100 MHz is indicated. In the calibration process, frequency compensation for dielectric dispersion of the PVC cable is also discussed. As for the time-domain measurement, the evaluation result of the fast transient impulsive noise of tr/tf: 10 ns emitted from a commercial power supply module is also discussed.

Machine Learning Regression Techniques for the Modeling of Complex Systems: An Overview

Recently, machine learning (ML) techniques have gained widespread diffusion, since they have been successfully applied in several research fields. This paper investigates the effectiveness of advanced ML regressions in two EMC applications. Specifically, support vector machine, least-squares support vector machine and Gaussian process regressions are adopted to construct accurate and fast-to-evaluate surrogate models able to predict the output variable of interest as a function of the system parameters. The resulting surrogates, built from a limited set of training samples, can be suitably adopted for both uncertainty quantification and optimization purposes. The accuracy and the key features of each of the considered machine learning techniques are investigated by comparing their predictions with the ones provided by either circuital simulations or measurements.

An Adaptive Sparse Anisotropic Polynomial-Chaos Expansion Algorithm Applied to EMC Problems

Various popular methods for Uncertainty Quantification (UQ) rely on the computation of Polynomial-Chaos (PC) expansions, which represent stochastic processes via convergent polynomial series. The computational cost for determining the expansion coefficients in such methods is related to the number of input variables, and is significantly enlarged in high-dimensional problems. On the other hand, the PC coefficients of the basis functions can be considered, in many cases, to form a sparse vector. This property is exploited in this paper to build PC models that are accurate and computationally efficient, by implementing the Orthogonal Matching Pursuit (OMP) as the solver, which can deal with underdetermined linear systems, assuming that their solution is sparse. In order to enhance the computational efficiency even further, the presented PC method is applied adaptively for various PC model orders, and the best solution is chosen according to a leave-one-out criterion. Finally, an optimally-designed multilayer electromagnetic filter for EMC applications is examined, considering ten or twenty stochastic design variables.

Impact of Temperature Variation on the Electromagnetic Shielding Behavior of Multilayer Shield for EMC Applications

Impact of Temperature Variation on the Electromagnetic Shielding Behavior of Multilayer Shield for EMC Applications

Optimized Planar Elliptical Dipole Antenna for UWB EMC Applications

This paper presents a novel method for optimizing a planar elliptical dipole antenna with elliptical slots, for ultrawideband electromagnetic compatibility applications. The antenna is required to achieve minimum return loss and boresight realized gain with an adequate gain flatness across the frequency range of 1–5 GHz. Such an antenna is a powerful tool for electromagnetic measurements, due to its very compact size and its wide operating bandwidth. The main optimization method used in this paper is the invasive weed optimization (IWO), which is a nature-inspired metaheuristic evolutionary algorithm. The conventional and a modified version of IWO are compared to other prior-art evolutionary algorithms, such as the particle swarm optimization and differential evolution. The comparison is performed by applying all the methods on a set of mathematical test functions and also on the specific antenna design problem presented in this paper. The comparative results demonstrate the superiority of the modified IWO over the other optimization methods.

The FEM‐BCI methods in EMC applications

AbstractThe paper reviews the finite element method‐boundary condition iteration family of hybrid numerical methods and shows their use in some electromagnetic problems arising in electromagnetic compatibility applications, ranging from static and quasi static to dynamic ones.

A computational approach to determine shielding effectiveness of carbon nanotube-based nanocomposites for EMC application

A computational method to determine the shielding effectiveness against electromagnetic interference of carbon nanotube (CNTs)-based nanocomposites through modelling of its electrical properties is presented. Specifically, simulations based on Ant Colony Optimization (ACO) were implemented to evaluate the electrical conductivity (σ) of CNTs (used as a filler in a polymer matrix) that formed electrical network inside a representative cuboid volume of the sample. A pseudo three-dimensional (3D) percolation model was developed to study the effects of random connectivity of CNTs to one another on the conductivity of nanocomposites. In our approach, both contact and intrinsic resistances were taken into account. The tunneling resistance between CNTs was also taken into account while dealing with single-walled CNTs (SWCNTs). A resistor network recognition method that optimizes connective paths was built using ACO method and conductivity was subsequently computed as a function of CNTs concentration. Then, the shielding effectiveness was computed using the conductivity data. It is remarkable that the calculated SE values as a function of frequency of EM waves at a constant weight percent of CNTs were in agreement with the experimental data for CNT-based nanocomposites reported in literature.

Impedance analysis of transmission line cells for EMC applications using Agros2D

When designing a TEM transmission line cell for electromagnetic compatibility susceptibility or immunity tests, its input impedance must be properly defined in order to deliver the maximum power to the device under test. The closed-form solution, relating the cell geometry with the characteristic impedance Zc, is possible only for the simplest “canonical” transmission line transverse cross-sections. The numerical methods must be used for arbitrary geometries instead. In this paper, we propose fast, robust, and accurate approach, based on fully hp-adaptive higher-order finite element electrostatic formulation. The approach is implemented in our in-house software Agros2D. The method applies for the impedance solution of an arbitrary TEM transmission line cell, any TEM transmission line with negligible losses, as well as for analyzing the effective electromagnetic properties of lossless complex stratified media.

Analysis of Nonuniform Transmission Lines With an Iterative and Adaptive Perturbation Technique

This paper presents an iterative and adaptive perturbation technique for the analysis of nonuniform transmission lines. Place-dependent variations of the per-unit-length parameters are interpreted as perturbations with respect to their average values along the line. This allows casting the governing equations for the corresponding perturbations of the voltages and currents as those of a uniform transmission line with distributed sources. Therefore, standard transmission line theory is used to calculate these perturbation terms. Specifically, perturbations of increasing order are computed iteratively starting from the solution of the unperturbed line. The accuracy is adaptively adjusted by setting a threshold on the convergence of the solution. The algorithm turns out to be simple to implement and very accurate, yet faster than traditional approaches based on the discretization of the line into uniform sections. The technique is validated through the analysis of several nonuniform transmission line structures of relevance in EMC applications, namely uniformly and nonuniformly twisted wire pairs as well as a cable bundle with lacing cords.

Innovative field receiver based on a new type of active rod antenna

An innovative approach to improve classical Rod Antennas is here described. This kind of antenna is used in EMC application since many years, but they have intrinsic design limitation and little improvement has been introduced to the design of the antenna in the past decades. Most of the limitation of a classical Rod Antenna can be overcome, thanks to a combination of technical solutions that can transform a rod antenna into a field receiver, yet maintaining the physical dimensions as required by civilian and military standards. An automatic preselector can also be added, as well as a preamplifier and attenuator banks. Moreover, a more convenient fiber optic output can be added as well, to avoid cable couplings and grounding effects.

Thin absorbers: operational principles and various realizations

In this paper we discuss electrically thin absorbers: thin lossy layers which can fully absorb (convert to heat) energy of electromagnetic waves falling on the layer's surface. Most often, thin absorbers are used as covers of metal bodies, and the goal is to eliminate reflections from conducting surfaces, with applications in EMC and stealth technology. However, in some applications it is necessary to absorb power in free-standing thin layers, for example, to create optically transparent windows which can fully absorb microwave radiation in a given frequency range. The goal of this paper is to explain the fundamental operational principles of thin absorbers, discuss fundamental limitations on their performance, and give a brief overview of recent research on thin absorbers for the microwave frequency range and EMC applications.

Black-box macromodeling and its EMC applications

The main idea of black-box macromodeling is to approximate the dynamic behavior of complex systems in terms of lowcomplexity models or equivalent circuits. Such compact models can be derived through robust numerical algorithms, such as the Vector Fitting scheme, starting from frequency- or time-domain responses of the system, and without any specific knowledge of its internal structure. The excellent accuracy that can be achieved, combined with the reduced size of the models, has led to a widespread adoption of this approach in several electrical and electronic applications, allowing designers to perform numerical simulations at the system level with high efficiency. This paper reviews the basics of black-box macromodeling and illustrates several application scenarios that are relevant for the EMC community, including Signal and Power Integrity, lossy transmission line modeling, electromagnetic full-wave simulation, network equivalencing and transformer modeling.

Completed careers

We have lost two major contributors to our EMC Society and EMC discipline. Dick Ford was a past member of the EMC Society Board of Directors and a passionate supporter of EMC applications especially in his US Navy job. Peter Richmond contributed to the development of EMC instrumentation which all test labs still use today. It is seldom that we feature a founder of major test instrumentation used primarily in immunity testing. Both are jewels of our craft. The details of their professional lives given below are a small sampling of all they did for our EMC discipline. We would require many more pages to do true justice to their lives but what is here is a good sampling of their EMC contributions.

Update on EMC Society sponsored standards

The reporting of our EMC Society standards activity will take a new tact in this article and the ones in future editions of the magazine. Rather than simply give a listing of the status of our standards and who is the WG chair, we will be focusing on new work that is being started on topics that have been brought to our attention in the past months. One source is discussions at the annual EMC symposium while other sources sometimes come straight from recent news and investigations that affect EMC application.

Energy Management Contracting - Research on the Development Pattern of Green Building

The article focused on practical application of EMC in the field of Green Building, especially analyzing obstacles in development of green buildings and the function produced by EMC.

Investigations on generation of very low side lobe difference patterns for EMC applications

Investigations on generation of very low side lobe difference patterns for EMC applications

Investigations on generation of very low side lobe difference patterns for EMC applications

Pattern synthesis is one of the most important aspects in antenna design. Arrays are more flexible to produce desired radiation characteristics. Difference patterns are usually generated with conventional techniques and there is less control on sidelobes. In view of this, techniques like genetic algorithm, particle swarm optimization and simulated annealing are applied to synthesize and produce such patterns optimally. The simulated patterns are produced for different array configurations and the patterns are presented in u domain.

Synthesis of Cosecant and Square Patterns for EMC applications

Many researchers made an attempt on Beam shaping of antennas useful for different applications in surveillance and tracking radars. In the present work, synthesis of line source and linear antenna array with uniform current amplitudes and weight functions is discussed. An iterative sampling method approach is being considered for implementation. In an iterative method, original radiation pattern which is close to the desired radiation pattern is generated by a standard synthesis method and a series of correction patterns are applied to it by adding correction patterns until the convergence is achieved. The iterative method is implemented for both line source and linear array for generating cosecant and square radiation patterns and their results are compared. The patterns designed are found to exhibit minimum suitable levels and they are useful to instigate the problems of EMC.

Application of Near-Field Emission Processing for Microwave Circuits under Ultra-Short Duration Perturbations

This paper is dealing with a time-frequency modeling method of electromagnetic (EM) near-field (NF) radiated by electronic devices excited by transient pulse signals. The model developed enables to calculate the EM NF maps at different distances from the given device and also the synthesis of radiation sources enabling to reproduce the field maps. The method proposed is based on the ultra wide band (UWB) frequency model of EM NF maps. The number of EM NF maps can be reduced by considering an innovative algorithm in order to establish simply the dipole model. Then, the transient model can be realized by considering the convolution between the transient excitation signals and the dipole-array model. The method proposed was validated by a standard 3D EM tool with a planar microstrip device excited by microwave signal modulating 1.25-GHz-carrier with 0.5-GHz-bandwidth. As expected, good correlation is found between results from simulation and the investigated modelling method. The method introduced in this paper is particularly useful for the investigation of time-domain emissions for EMC applications by considering transient EM interferences (EMIs).

Combined FVTD/PSTD Schemes with Enhanced Spectral Accuracy for the Design of Large-Scale EMC Applications

A generalized conformal time-domain method with adjustable spectral accuracy is introduced in this paper for the consistent analysis of large-scale electromagnetic compatibility problems. The novel 3-D hybrid schemes blend a stencil-optimized finite-volume time-domain and a multimodal Fourier-Chebyshev pseudo-spectral time-domain algorithm that split the overall space into smaller and flexible areas. A key asset is that both techniques are updated independently and interconnected by robust boundary conditions. Also, combining a family of spatial derivative approximators with controllable precision in general curvilinear coordinates, the proposed method launches a conformal field flux formulation to derive electromagnetic quantities in regions with fine details. For advanced grid reliability at dissimilar media interfaces, dispersion-reduced adaptive operators, which assign the proper weights to each spatial increment, are developed. So, the resulting discretization yields highly rigorous and computationally affordable simulations, devoid of lattice errors. Numerical results, addressing detailed comparisons of various realistic applications with reference or measurement data verify our methodology and reveal its significant applicability.