Zouheir Riah

A 3-D Near-Field Modeling Approach for Electromagnetic Interference Prediction

This paper presents, through an illustrative example, a 3-D modeling approach to predict the electromagnetic interference (EMI) between complex electronic devices and interconnections placed in the near-field region. Three different analytic coupling formulations have been investigated along with a 3-D-emission model to evaluate the induced voltages in transmission line (TL) extremities in the case of both matched and mismatched TL configurations. The proposed modeling method is successfully validated by comparison with numerical results using electromagnetic (EM) simulation tools and experimental results using near-field measurement. The obtained EM coupling results are more accurate than other traditional 2-D models.

Modeling the Electromagnetic Radiation of Passive Microwave Components Using a Near-Field Scanning Method

This paper presents a heuristic optimized model for describing the electric- and magnetic-radiated emissions from passive microwave components. The main idea has been derived from a previously built model at the Research Institute for Embedded Electronic Systems, which models only the radiated magnetic field. The modeling procedure is based on the use of elementary dipoles. The model extraction is a two-step technique: extraction of the initial dipole parameters (namely their orientation and currents) and an optimization. The Levenberg-Marquardt algorithm is used in order to optimize the dipole parameters, keeping in mind their physical sense. The tangential components of the measured magnetic field are used to build the model.

A Novel Approach for Modeling Near-Field Coupling With PCB Traces

This paper presents a novel modeling approach for predicting the response of a printed circuit board (PCB) trace excited by a nonuniform electromagnetic (EM) radiated field from complex electronic components. The proposed approach is analytic and it is based on transmission line model with distributed sources taking into account the effect of the effective relative permittivity εreff of the PCB surrounding medium. The modeling procedure is a two-step approach: three-dimensional radiated emission modeling of the electronic component, source of EM disturbance, and using a set of equivalent sources followed by the computation of the induced voltages in the trace terminals referring to analytic coupling formulations. Comparison between modeled, numerical, and measured results enables us to validate the proposed model.

Postprocessing of Near-Field Measurement Based on Neural Networks

This paper presents postprocessing based on neural network (NN) models to reconstruct the magnetic near-field profile with an improved spatial resolution for one or different frequencies. The models aim at decreasing the time required to perform near-field electromagnetic compatibility (EMC) measurements. The multilayer perceptron (MLP) NNs are used to determine the magnetic near field radiated by passive devices and power electronics components. An optimization method, called the split-sample method, is implemented to determine the structures of the NN. The results obtained with the proposed method are compared with the measurement results. A graphic interface (GUI) is created to simplify the utilization of the developed NN models.

Prediction of 3D-near field coupling between a toroïdal inductor and a transmission line

This paper presents an application of a 3D near-field modeling approach to predict the coupling between a toroïdal inductor (TI) and a transmission line (TL) placed in its vicinity. The TI equivalent 3D emission model is combined with analytic coupling formulations to compute the induced voltages in different configurations of the victim line. The proposed modeling procedure is less consuming in terms of computing times, preserves DUT confidentiality and offers an accurate electromagnetic interference (EMI) prediction. Results enable designers to optimize components positions inside electronic boards to guarantee electromagnetic compatibility (EMC) of the whole system.

Influence of car body materials on the common-mode current and radiated emissions induced by automotive shielded cables

In order to reduce the radiated emissions due to high power converters in electric and hybrid vehicles, shielded cables are systematically used. This paper presents measurement results of the common-mode current and the radiated magnetic field produced by a shielded cable when different car body materials are considered. A simple but sufficiently representative measurement setup has been defined and constructed to take into account the impact of the new materials considered in automotive industry, such as low conductive carbon fiber reinforced epoxy. The results obtained allow evaluating the magnetic field produced between 10 kHz and 10 MHz when the shielded cable is either inside or outside the car body.

On the radiated electromagnetic emission modelling of on-chip microwave components

A radiated emission model, scaled, optimized, and compatible to modelling “on-chip” microwave devices is presented in this paper. The model has been inspired from a previously existing model at IRSEEM, which predicts only the radiated magnetic field. The proposed model predicts the radiated electromagnetic (EM) emissions of components of very small form factor. An optimization procedure has been implemented in order to extract the model parameters, taking into account their physical sense. The model is applied to an “on-chip” microstrip patch antenna, designed and simulated in Ansoft HFSS. The antenna is built on a High Resistivity Silicon substrate and resonates at 20 GHz. Promising and encouraging results have been obtained for the modelled radiated EM fields. Our model is proven suitable to apply on System-in-package and System-on-Chip devices integrating wireless system within itself.

Modeling the Time-Harmonic Electromagnetic Emissions of Microwave Circuits

This paper presents a simple and practical method to reproduce and predict the time-domain behavior of the radiated electromagnetic fields of microwave circuits. The previously developed frequency-domain model is extended toward predicting the large-band electromagnetic radiations and thereby the time-harmonic fields. Fourier-series-based method is used in order to transform the frequency-domain near-field measurement data into time domain for digital applications. A cutting-edge extraction procedure is developed so as to extract the large-band model parameters in a single step. The modeling method is validated on a high frequency transmission line and on a hybrid coupler. The modeled results are compared with time-domain simulations performed in CST Microwave Studio.

Estimation of the electromagnetic field radiated by a microwave circuit encapsulated in a rectangular cavity

A signal, propagating in an electronic circuit enclosed in a metal cavity, can excite the cavitys natural modes. In the context of RF amplifier reliability study against electromagnetic stress, a precise characterization of radiated emissions is imposed on us. This characterization is often achieved by measuring the near field of the circuit without enclosing it in a cavity (the top cover of the cavity is kept open), which does not always resemble the electromagnetic behavior when the same circuit is shielded within the cavity. In this work, we study the changes in the cartographies (electromagnetic fields mapping) of the electromagnetic field radiated under the influence of the metal cavity and we present a method to estimate the radiated field in the cavity from measurements made in the absence of the cavity. This method is validated for all frequencies except resonant frequencies.

A method to overcome the load connection restrictions in the combined MoM/MTL approach

This work proposes a mathematical transformation for the sources and the linear loads to overcome the cable-load connection restrictions applied to a braided shielded cable in the combined MoM/MTL approach. When the assumptions of the transmission line theory are nonvalid because of a non-direct current flowing below the shielded cable, numerical techniques for solving EMC problems have to be deployed. The proposed model is based on an association of voltage sources and current-controlled voltage sources to reproduce the behavior of the real sources and loads at the terminations of a shielded cable. In order to validate this approach, a measurement setup has been proposed to take into account the influence of a non-direct current flowing through a ground plane with a large aperture. The measurement results obtained between 10 kHz and 300 MHz, where the main radio reception EMC issues exist, have been compared to the combined MoM/MTL modified approach. The excellent comparison results prove that combining full-wave numerical techniques and the proposed mathematical transformation can overcome the cable-load conditions in complex electromagnetic environments.