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Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper describes the application of the finite-difference time-domain method (fdtd) to the calculation of vlf-lf radiowave propagation in the Earth-ionosphere waveguide. Special techniques have been developed to render the computational time acceptable, namely the use of a moving computational domain and the introduction of an artificial anisotropy in view of reducing the anisotropy of the fdtd scheme. Numerical experiments are provided to illustrate the good agreement of the fdtd method with the waveguide method. Cet article décrit l’application de la méthode des différences finies temporelles au calcul de la propagation des ondes kilométriques et myriamétriques (vlf-lf) dans le guide d’onde Terre-ionosphère. Des techniques particulières sont mises en oeuvre pour rendre le temps de calcul acceptable, à savoir l’utilisation d’un volume de calcul mobile et l’introduction d’une anisotropie artificielle destinée à réduire l’anisotropie du schéma numérique. Des résultats de calcul illustrent le très bon accord de la méthode des différences finies et de la méthode des modes. [ABSTRACT FROM AUTHOR]

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper discusses the most recent progress in developing effective physics-based models for devices operating at millimeter-wave frequencies. The model is based on coupling dynamic electromagnetic wave solutions with carrier transport models. The potentials of this modeling approach for both device simulation and the global simulation of millimeter-wave circuits are demonstrated. Results comparing the full-wave model developed with conventional electrostatic models are provided through the simulation of different microwave transistors. The ability of the model to detect traveling wave effects, such as phase mismatch between the input and output electrodes of a conventional transistor, and their effects on the device gain are also provided. Results from the simulation of an air-bridged gate Mesfet, designed to reduce traveling wave effects in high frequency transistors and solve the problem associated with high gate resistance, are illustrated and discussed. Finally, results showing the ability of this technique to model the nonlinearity and the harmonic distortion are provided through the simulation of an amplifier circuit. Cet article discute des plus récents progrès dans les modèles physiques des dispositifs fonctionnant en ondes millimétriques. Le modèle utilise le couplage entre ondes électromagnétiques et les équations dynamiques des porteurs de charge. On montre les potentialités de ce modèle pour la simulation des circuits en ondes millimétriques. Une comparaison entre cette méthode et la méthode classique de l’électrostatique est réalisée par l’intermédiaire de la simulation de différents transistors microondes. L’aptitude du modèle à détecter des effets d’onde progressive, comme la désadaptation de phase entre l’entrée et la sortie d’un transistor ordinaire, et leurs effets sur le gain sont également fournis. Les résultats de la simulation d’une porte Mesfet pontée, conçue pour réduire les effets de propagation et résoudre le problème associé à la forte résistance de porte, sont illustrés et commentés. Enfin, des résultats montrant la capacité du modèle à prendre en compte les non-linéarités ainsi que la distorsion harmonique sont fournis à trovers la simulation d’un circuit amplificateur. [ABSTRACT FROM AUTHOR]

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

L'objet de cet article est de calculer la réponse à une onde plane de champ électromagnétique impulsionnel (temps de montée 10 ns, largeur à mihauteur 200 ns) d'une antenne Yagi fonctionnant à 100 MHz. Deux calculs différents sont envisagés. Le premier consiste à résoudre les équations intégrales du problème dans le domaine fréquentiel puis à pratiquer une inversion de Fourier. Le second, temporel, résout les équations de Maxwell dans tout l'espace par une méthode aux différences finies. C'est le calcul temporel qui se révèle ici le plus efficace. La réponse de l'antenne met en évidence une période de régime transitoire suivie d'une période de régime établi. Si le régime établi montre l'effet de directivité caractéristique de l'antenne dans son mode de fonctionnement nominal, le régime transitoire dépend de la configuration d'illumination d'une façon différente. Ce dernier point s'interprète par la combinaison des modes commun et différentiel propres à l'élément alimenté (un doublet replié). The purpose of this paper is to compute the response of a 100 MHz Yagi antenna to an electromagnetic pulse (rise time 10 ns, pulse width 200 ns). Two different techniques are investigated. With the first one, integral equations are solved in the frequency domain and then a Fourier transform is performed. With the second one, Maxwell's equations are solved everywhere within the space around the antenna, using a finite difference method in the time domain. To solve the very problem dealt with, the time domain method turns out to be the more efficient. The overall antenna response can be divided into a short time waveform followed by a long time one. The long time response exhibits the same directivity effect as the one expected from the antenna when operated at its nominal frequency. The short time response depends also on the azimuth but in a rather different way. That last point can be accounted for when combining the differential and common modes of the driven folded dipole. [ABSTRACT FROM AUTHOR]

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

La diffraction en régime transitoire est traitée directement dans le domaine temporel par une méthode originale utilisant la théorie des distributions. Pour les obstacles métalliques parfaitement conducteurs, cette approche généralise les solutions existantes dans la littérature, mais permet aussi d'établir de nouvelles équations intégrales donnant la solution des problèmes de diffraction à deux dimensions (l'onde et l'obstacle présentent une symétrie de translation ou de révolution). Des applications dans le domaine de la protection d'installations de télécommunications contre les impulsions Em ( foudre, impulsion Em d'origine nucléaire, etc). sont présentées]. Transient scattering problem by perfectly conducting bodies is treated, directly in time domain, using the distribution theory. New integral equations for solving two dimensional scattering problems are established. Applications to metallic structures responses to electro-magnetic pulses ( Emp) illumination are presented. [ABSTRACT FROM AUTHOR]

Après avoir montré comment est obtenue l'équation intégrale du champ électrique pour les problèmes à une et deux dimensions, l'auteur indique la procédure employée pour la résolution. Cette procédure est basée sur l'emploi de la méthode des moments et a conduit à l'élaboration d'algorithmes programmés sur ordinateur dont les limites d'application sont précisées. Les résultats présentés sont relatifs à l'examen de quelques cas canoniques. The author is studying the electric field integral equation in the time domain for one and two dimensional surfaces respectively. The equations are solved with the moment method. The algorithms are presented. Special attention is given to their differences and limitations. A few results are presented for canonical cases. [ABSTRACT FROM AUTHOR]

Le problème du calcul du courant induit par une onde incidente sur un conducteur enterré, isolé et situé au voisinage du sol, est analysé. La solution est recherchée dans le domaine fréquentiel sur un conducteur infini. Ceci permet d'éviter le calcul des intégrales de Sommerfeld en leur substituant des intégrales qui se calculent analytiquement. Le courant induit sur un conducteur de dimension finie s'obtient en ajoutant les courants réfléchis aux extrémités pour les différents ordres successifs de réflexion. An analytical result for the current induced by a plane incident wave on a thin straight insulated wire buried in the ground and parallel to the interface is presented. Two methods are presented to solve this problem in the frequency domain; the first one uses the current on an infinite wire; the current induced on a finite wire is obtained adding to the preceding result the reflected currents of different orders. The second uses the reflection coefficients of the transmission line theory. The results are compared with those obtained from another method in which the Sommerfeld integrals are numerically evaluated. [ABSTRACT FROM AUTHOR]

Le problème du calcul du courant induit par une onde incidente sur un conducteur aérien, rectiligne, filiforme, situé au voisinage du sol et parallèle à l'interface airsol est analysé. La solution recherchée est dans le domaine fréquentiel sur un conducteur infini. Ceci permet d'éviter le calcul numérique des intégrales de Sommerfeld en leur substituant des intégrales qui se calculent analytiquement. Le courant induit sur un conducteur de dimension finie s'obtient en ajoutant les courants réfléchis aux extrémités pour les différents ordres successifs de réflexion. An analytical result for the current induced by an incident wave on a thin straight wire located in the vicinity of the ground and parallel to the interface is presented. Two methods are presented to solve this problem in the frequency domain. The first one uses the current on an infinite wire; the current induced on a finite wire is obtained adding to the preceding solution the reflected currents of different orders. The second uses the reflection coefficient of the transmission line theory. The results are compared with those obtained from another method in which Sommerfeld integrals are numerically evaluated. [ABSTRACT FROM AUTHOR]