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V. Gobin

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John Jairo Pantoja Acosta

Universidad Nacional de Colombia (National University of Colombia)

Universidad Politécnica de Valencia

Demetrio Labate

University of Houston

Los Alamos National Laboratory

Danilo Erricolo

University of Illinois at Chicago

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Papers by V. Gobin

Issue 5-December 2012-Indirect Effects of Lightning on Aircraft and Rotorcraft Lightning Hazards to Aircraft and Launchers Indirect Effects of Lightning on Aircraft and Rotorcraft

T his article discusses issues related to indirect lightning on aircraft/rotorcraft. The standard... more T his article discusses issues related to indirect lightning on aircraft/rotorcraft. The standard waveforms used for qualifying the vulnerability of a system are introduced, with their frequency spectrum. The identification of the elementary EM coupling phenomenon allows the understanding of the key drivers of the current distribution and field scattering on a complex structure. The system level EM coupling analysis starts with examples of cable-measurements on real aircraft/rotorcraft, from which simple models are derived in order to understand the origin of the resulting waveforms. Various ways of protection are then proposed, ranging from passive to active solutions. Finally, despite limitations, 3D EM modeling is presented as an efficient complement to scale-one tests. The article concludes on the validity of current knowledge on indirect lightning for future aircraft designs.

Experimental study of the interaction between an arc and an electrically floating structure

Modelling of electromagnetic wave penetration through loaded apertures

International Journal of Numerical Modelling: Electronic Networks, Devices and Fields, 1991

Calculation of the electromagnetic field diffracted by an aperture situated in a perfectly conduc... more Calculation of the electromagnetic field diffracted by an aperture situated in a perfectly conducting ground plane can be made through the well-known theory of polarizabilities. However, simple expressions are only obtained under conditions which are not often fulfilled in electromagnetic compatibility problems since, for example, the disturbing field incident on the aperture must be considered as a uniform one. Furthermore, if the aperture is loaded by a low conducting material, available approximate formulas are only valid for a small circular hole. In this paper, we present a numerical approach based on the determination of the equivalent magnetic current distributed on the surface of the aperture. This distribution is the solution of an integral equation solved by the method of moments. This formulation allows us to take the surface impedance of a loading material and the contact resistance between this material and the rim into account. The validation of the computer code is shown by comparing computed and analytical results on some typical examples. Few applications are also described.

A new local model for small apertures in a multi-domain approach

2009 IEEE Antennas and Propagation Society International Symposium, 2009

The surface impedance - A pertinent parameter to describe finite conductivity materials in numerical codes

This paper deals with the description of finite conductivity materials in numerical codes solving... more This paper deals with the description of finite conductivity materials in numerical codes solving Maxwell's equations. It is shown that the surface impedance concept leads to a good representation in many practical cases, and numerical results are validated by comparison with analytical formulas. The applicability limits of the surface impedance modeling is finally discussed.

Validation of electromagnetic-topology concepts on a complex structure

The paper describes the main results of a series of tests conducted in 1991, in a collaboration b... more The paper describes the main results of a series of tests conducted in 1991, in a collaboration between ONERA and CEG, with the aim of demonstrating the feasibility and advantages of the topological analysis of a complex structure. The elements of a modular panel (composed of elementary volumes connected by a network of multifilamentary cables) were characterized by different experimental and theoretical methods. These data were entered into in the CRIPTE code, based on a simulation of an array of multiconductor transmission lines subjected to an electromagnetic disturbance. Numerous experimental results, measured in the frequency and time domains, were obtained in the laboratory and via simulator, and simulated with success by the topological method.

Modeling of electrically thick materials theoretical and experimental aspects

The shielding effectiveness of modern aircraft depends upon the nature and the electromagnetic pr... more The shielding effectiveness of modern aircraft depends upon the nature and the electromagnetic properties of the materials used. It was shown that thin materials are modeled well by a sheet surface impedance. Unfortunately, this formalism fails in the high frequency domain (when skin effect occurs) and when the materials are physically thick. The purpose is to propose a general formalism that renders the skin effect and can be used with multilayered samples. These electrically thick materials are studied using symmetrical boundary conditions applied to tangential fields. The domain of validity of the method is discussed and experimental validations are presented.

Conductive materials surface impedance measurements

A method used to measure the surface impedance of a material consists of measuring shielding effe... more A method used to measure the surface impedance of a material consists of measuring shielding effectiveness of a sample of this material interposed between a radiating antenna and a receiving antenna. Quantitative results obtained in the case of a loaded aperture in an infinite conductive plane are summarized. The following drawbacks of this method are pointed out: (1) measurements depend upon the geometry of the sample and upon the electrical connection between the sample and the conductive plane, and (2) the measurement must be carried out on both sides of the sample. A new method avoiding these drawbacks is given here. An analytical calculation makes it possible to study the influence of various geometrical parameters. Theoretical results are compared to experimental results for samples in which surface impedances varies from several microohm to several ohm.

Overlapping method for EMC applications applied to aperture models in domain decomposition method

2010 IEEE Antennas and Propagation Society International Symposium, 2010

Aperture models in domain decomposition method for coupled-cavity systems

2009 International Conference on Electromagnetics in Advanced Applications, 2009

In this article is a problem of electromagnetic compatibility (EMC) presented bringing in several... more In this article is a problem of electromagnetic compatibility (EMC) presented bringing in several cavities, mutually coupled between holes of small size with respect to the wavelength. The coupling function between cables placed in multiple cavities is estimated by a numerical method based on a topological approach. The intermediate data of the problem allow to bring to highlight the various types of coupling through apertures (the magnetic tangential modes and the normal electric mode) in particular the coupling between these modes which are due to the box's geometry.

Système expérimental de cavités couplées modélisé par une approche topologique

On présente dans cet article un problème de compatibilité électromagnétique (CEM) faisant interve... more On présente dans cet article un problème de compatibilité électromagnétique (CEM) faisant intervenir plusieurs cavités, couplées entre elles par des ouvertures de taille petite devant la longueur d’onde. La fonction de couplage entre les câbles placés dans diverses cavités est évaluée par une méthode numérique basée sur l’approche topologique. Les données intermédiaires du problème permettent de mettre en évidence les différents types de couplage à travers les ouvertures (les modes magnétiques tangentiels et le mode électrique normal) et notamment les échanges d’énergie entre ces modes, provoqués par les interactions électromagnétiques dans les caissons.

Ariane 5 Lightning Verification Plan

SAE Technical Paper Series, 1999

Study and Characterization of Gaskets in the Frequency Band [100 kHz - 100 MHz]

SAE Technical Paper Series, 1999

Communication to : ICOLSE 99 International conference on lightning and static electricity, Toulou... more Communication to : ICOLSE 99 International conference on lightning and static electricity, Toulouse (FR), June 22-24, 1999SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1999 n.96 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

La modélisation électromagnétique au bénéfice des études d'antennes, de signatures radar et de compatibilité électromagnétique : le projet PAME

Revue de l'Electricité et de l'Electronique, 2002

En 20 ans, la modelisation electromagnetique s'est extirpee du domaine academique pour conque... more En 20 ans, la modelisation electromagnetique s'est extirpee du domaine academique pour conquerir une place primordiale dans la conception et le developpement de systemes modernes. De nombreuses methodes numeriques existent pour resoudre les equations fondamentales de l'electro-magnetisme. On cherche ici a guider un lecteur curieux et lui faire palper les caracteristiques dominantes de ces techniques, sans equations... Des approches nouvelles et prometteuses juxtaposent dorenavant ces techniques elementaires par decomposition en domaines des geometries complexes. On rend alors le pouvoir de decision a l'utilisateur des codes numeriques qui peut adapter sa methodologie et choisir les outils correspondant a ces besoins.

Methods for computing electromagnetic disturbances inside structures that include composite materials. I - Basic principles. II - Experimental data

An attempt is made to establish the theoretical bases for computing the voltages and currents set... more An attempt is made to establish the theoretical bases for computing the voltages and currents set up by diffraction on randomly placed single-wire lines inside cylindrical structures. The apertures are either open or closed off by carbon composite panels and by diffusion on single-wire lines placed inside a carbon composite cylinder. The tests were carried out in the sinusoidal mode and were used for a comparison of computed and experimental data for different electromagnetic coupling configurations. The determination of equivalent generators due to the diffusion phenomenon is discussed.

Low-frequency electromagnetic coupling across loaded apertures with joints

Annales Des Télécommunications - AdT, 1993

The diffraction of an electromagnetic wave across an aperture which is bounded by joints of unifo... more The diffraction of an electromagnetic wave across an aperture which is bounded by joints of uniform or nonuniform resistance, is studied with the aid of a numerical code based on the Method of Moments. For a joint of uniform resistance, the results obtained are in good agreement with the analytical results produced by the Casey model. To our knowledge, no model exists for joints in which resistance is not evenly distributed. In this case, the results obtained using the numerical code demonstrate that the attenuation of the equivalent dipole decreases until, beyond a certain frequency, it reaches a constant value. This is in contrast to the case of the uniform joint where the dipolar attenuation behaves as a first-order low-pass filter.

Simulation of radiation from an antenna mounted on a vehicle by a multilevel QR compression algorithm

IEEE Microwave and Wireless Components Letters, 2005

Application of multi-domain decomposition method to solve EMC problem on an aeroplane

Electronics Letters, 1997

The authors describe a multi-domain decomposition method using an FVTD technique for the resoluti... more The authors describe a multi-domain decomposition method using an FVTD technique for the resolution of an electromagnetic problem on vehicles composed of several volumes. In particular, they evaluate the current on a cable inside the volume of an aeroplane. The results obtained show an important gain in time compared to a complete FVTD method.

Détermination de la matrice admittance d’une ouverture sur un système faradisé

-Nous considérons dans cet article une problématique de couplage d'une agressionélectromagnétique... more -Nous considérons dans cet article une problématique de couplage d'une agressionélectromagnétique sur un système faradisé, dans un contexte de CompatiblitéÉlectroMagnétique (CEM). L'évaluation du niveau de couplage sur l'équipement est alors déterminé par une méthode Multi-Domaines (MD), en calculant préalablement une matrice [Y] de couplage sur l'ouverture, interprétée par 3 composantes, deux magnétiques et uneélectrique. On discutera des parties réactives et rayonnées de ces dernières, pour les matrices interne et externe.

Fonctions de base spécifiques pour un modèle d’ouverture dans une approche de décomposition de domaines

Issue 5-December 2012-Indirect Effects of Lightning on Aircraft and Rotorcraft Lightning Hazards to Aircraft and Launchers Indirect Effects of Lightning on Aircraft and Rotorcraft

T his article discusses issues related to indirect lightning on aircraft/rotorcraft. The standard... more T his article discusses issues related to indirect lightning on aircraft/rotorcraft. The standard waveforms used for qualifying the vulnerability of a system are introduced, with their frequency spectrum. The identification of the elementary EM coupling phenomenon allows the understanding of the key drivers of the current distribution and field scattering on a complex structure. The system level EM coupling analysis starts with examples of cable-measurements on real aircraft/rotorcraft, from which simple models are derived in order to understand the origin of the resulting waveforms. Various ways of protection are then proposed, ranging from passive to active solutions. Finally, despite limitations, 3D EM modeling is presented as an efficient complement to scale-one tests. The article concludes on the validity of current knowledge on indirect lightning for future aircraft designs.

Experimental study of the interaction between an arc and an electrically floating structure

Modelling of electromagnetic wave penetration through loaded apertures

International Journal of Numerical Modelling: Electronic Networks, Devices and Fields, 1991

Calculation of the electromagnetic field diffracted by an aperture situated in a perfectly conduc... more Calculation of the electromagnetic field diffracted by an aperture situated in a perfectly conducting ground plane can be made through the well-known theory of polarizabilities. However, simple expressions are only obtained under conditions which are not often fulfilled in electromagnetic compatibility problems since, for example, the disturbing field incident on the aperture must be considered as a uniform one. Furthermore, if the aperture is loaded by a low conducting material, available approximate formulas are only valid for a small circular hole. In this paper, we present a numerical approach based on the determination of the equivalent magnetic current distributed on the surface of the aperture. This distribution is the solution of an integral equation solved by the method of moments. This formulation allows us to take the surface impedance of a loading material and the contact resistance between this material and the rim into account. The validation of the computer code is shown by comparing computed and analytical results on some typical examples. Few applications are also described.

A new local model for small apertures in a multi-domain approach

2009 IEEE Antennas and Propagation Society International Symposium, 2009

The surface impedance - A pertinent parameter to describe finite conductivity materials in numerical codes

This paper deals with the description of finite conductivity materials in numerical codes solving... more This paper deals with the description of finite conductivity materials in numerical codes solving Maxwell's equations. It is shown that the surface impedance concept leads to a good representation in many practical cases, and numerical results are validated by comparison with analytical formulas. The applicability limits of the surface impedance modeling is finally discussed.

Validation of electromagnetic-topology concepts on a complex structure

The paper describes the main results of a series of tests conducted in 1991, in a collaboration b... more The paper describes the main results of a series of tests conducted in 1991, in a collaboration between ONERA and CEG, with the aim of demonstrating the feasibility and advantages of the topological analysis of a complex structure. The elements of a modular panel (composed of elementary volumes connected by a network of multifilamentary cables) were characterized by different experimental and theoretical methods. These data were entered into in the CRIPTE code, based on a simulation of an array of multiconductor transmission lines subjected to an electromagnetic disturbance. Numerous experimental results, measured in the frequency and time domains, were obtained in the laboratory and via simulator, and simulated with success by the topological method.

Modeling of electrically thick materials theoretical and experimental aspects

The shielding effectiveness of modern aircraft depends upon the nature and the electromagnetic pr... more The shielding effectiveness of modern aircraft depends upon the nature and the electromagnetic properties of the materials used. It was shown that thin materials are modeled well by a sheet surface impedance. Unfortunately, this formalism fails in the high frequency domain (when skin effect occurs) and when the materials are physically thick. The purpose is to propose a general formalism that renders the skin effect and can be used with multilayered samples. These electrically thick materials are studied using symmetrical boundary conditions applied to tangential fields. The domain of validity of the method is discussed and experimental validations are presented.

Conductive materials surface impedance measurements

A method used to measure the surface impedance of a material consists of measuring shielding effe... more A method used to measure the surface impedance of a material consists of measuring shielding effectiveness of a sample of this material interposed between a radiating antenna and a receiving antenna. Quantitative results obtained in the case of a loaded aperture in an infinite conductive plane are summarized. The following drawbacks of this method are pointed out: (1) measurements depend upon the geometry of the sample and upon the electrical connection between the sample and the conductive plane, and (2) the measurement must be carried out on both sides of the sample. A new method avoiding these drawbacks is given here. An analytical calculation makes it possible to study the influence of various geometrical parameters. Theoretical results are compared to experimental results for samples in which surface impedances varies from several microohm to several ohm.

Overlapping method for EMC applications applied to aperture models in domain decomposition method

2010 IEEE Antennas and Propagation Society International Symposium, 2010

Aperture models in domain decomposition method for coupled-cavity systems

2009 International Conference on Electromagnetics in Advanced Applications, 2009

In this article is a problem of electromagnetic compatibility (EMC) presented bringing in several... more In this article is a problem of electromagnetic compatibility (EMC) presented bringing in several cavities, mutually coupled between holes of small size with respect to the wavelength. The coupling function between cables placed in multiple cavities is estimated by a numerical method based on a topological approach. The intermediate data of the problem allow to bring to highlight the various types of coupling through apertures (the magnetic tangential modes and the normal electric mode) in particular the coupling between these modes which are due to the box's geometry.

Système expérimental de cavités couplées modélisé par une approche topologique

On présente dans cet article un problème de compatibilité électromagnétique (CEM) faisant interve... more On présente dans cet article un problème de compatibilité électromagnétique (CEM) faisant intervenir plusieurs cavités, couplées entre elles par des ouvertures de taille petite devant la longueur d’onde. La fonction de couplage entre les câbles placés dans diverses cavités est évaluée par une méthode numérique basée sur l’approche topologique. Les données intermédiaires du problème permettent de mettre en évidence les différents types de couplage à travers les ouvertures (les modes magnétiques tangentiels et le mode électrique normal) et notamment les échanges d’énergie entre ces modes, provoqués par les interactions électromagnétiques dans les caissons.

Ariane 5 Lightning Verification Plan

SAE Technical Paper Series, 1999

Study and Characterization of Gaskets in the Frequency Band [100 kHz - 100 MHz]

SAE Technical Paper Series, 1999

Communication to : ICOLSE 99 International conference on lightning and static electricity, Toulou... more Communication to : ICOLSE 99 International conference on lightning and static electricity, Toulouse (FR), June 22-24, 1999SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1999 n.96 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

La modélisation électromagnétique au bénéfice des études d'antennes, de signatures radar et de compatibilité électromagnétique : le projet PAME

Revue de l'Electricité et de l'Electronique, 2002

En 20 ans, la modelisation electromagnetique s'est extirpee du domaine academique pour conque... more En 20 ans, la modelisation electromagnetique s'est extirpee du domaine academique pour conquerir une place primordiale dans la conception et le developpement de systemes modernes. De nombreuses methodes numeriques existent pour resoudre les equations fondamentales de l'electro-magnetisme. On cherche ici a guider un lecteur curieux et lui faire palper les caracteristiques dominantes de ces techniques, sans equations... Des approches nouvelles et prometteuses juxtaposent dorenavant ces techniques elementaires par decomposition en domaines des geometries complexes. On rend alors le pouvoir de decision a l'utilisateur des codes numeriques qui peut adapter sa methodologie et choisir les outils correspondant a ces besoins.

Methods for computing electromagnetic disturbances inside structures that include composite materials. I - Basic principles. II - Experimental data

An attempt is made to establish the theoretical bases for computing the voltages and currents set... more An attempt is made to establish the theoretical bases for computing the voltages and currents set up by diffraction on randomly placed single-wire lines inside cylindrical structures. The apertures are either open or closed off by carbon composite panels and by diffusion on single-wire lines placed inside a carbon composite cylinder. The tests were carried out in the sinusoidal mode and were used for a comparison of computed and experimental data for different electromagnetic coupling configurations. The determination of equivalent generators due to the diffusion phenomenon is discussed.

Low-frequency electromagnetic coupling across loaded apertures with joints

Annales Des Télécommunications - AdT, 1993

The diffraction of an electromagnetic wave across an aperture which is bounded by joints of unifo... more The diffraction of an electromagnetic wave across an aperture which is bounded by joints of uniform or nonuniform resistance, is studied with the aid of a numerical code based on the Method of Moments. For a joint of uniform resistance, the results obtained are in good agreement with the analytical results produced by the Casey model. To our knowledge, no model exists for joints in which resistance is not evenly distributed. In this case, the results obtained using the numerical code demonstrate that the attenuation of the equivalent dipole decreases until, beyond a certain frequency, it reaches a constant value. This is in contrast to the case of the uniform joint where the dipolar attenuation behaves as a first-order low-pass filter.

Simulation of radiation from an antenna mounted on a vehicle by a multilevel QR compression algorithm

IEEE Microwave and Wireless Components Letters, 2005

Application of multi-domain decomposition method to solve EMC problem on an aeroplane

Electronics Letters, 1997

The authors describe a multi-domain decomposition method using an FVTD technique for the resoluti... more The authors describe a multi-domain decomposition method using an FVTD technique for the resolution of an electromagnetic problem on vehicles composed of several volumes. In particular, they evaluate the current on a cable inside the volume of an aeroplane. The results obtained show an important gain in time compared to a complete FVTD method.

Détermination de la matrice admittance d’une ouverture sur un système faradisé

-Nous considérons dans cet article une problématique de couplage d'une agressionélectromagnétique... more -Nous considérons dans cet article une problématique de couplage d'une agressionélectromagnétique sur un système faradisé, dans un contexte de CompatiblitéÉlectroMagnétique (CEM). L'évaluation du niveau de couplage sur l'équipement est alors déterminé par une méthode Multi-Domaines (MD), en calculant préalablement une matrice [Y] de couplage sur l'ouverture, interprétée par 3 composantes, deux magnétiques et uneélectrique. On discutera des parties réactives et rayonnées de ces dernières, pour les matrices interne et externe.

Fonctions de base spécifiques pour un modèle d’ouverture dans une approche de décomposition de domaines