Jean-Pierre Damiano

Comments on "A new model for calculating the input impedance of coax-fed circular microstrip antennas with and without air gaps" [with reply]

For original paper by Abboud et al. see IEEE Trans. Antennas Propagat., vol.38, p.1882-5 (1990). In the original paper, the resonance frequency of coax-fed circular microstrip antennas with and without air gaps has been modeled (in its Section III) by incorporating and rearranging some results previously reported by others. The present author, while working with the formulas of that Section III noticed a discrepancy in (8) and (9). This has been investigated thoroughly and the observations are presented. A brief reply is given by Damiano et al.

Oxygen transfer from iron nitrates in the presence of 2-(diphenylphosphine oxide)pyridine (OPPh2py). Molecular structure of Fe(NO3)2Cl(OPPh2py) · CH2Cl2

Abstract [Fe(Cl) 4 ](Fe(NO 3 ) 2 (OPPh 2 py) 2 ], 2 , and [Fe(NO 3 ) 2 (Cl)(OPPh 2 py)], 3 , were obtained when [Fe(Cl) 4 ][Fe(Cl) 2 (OPPh 2 py) 2 ], 1 , was allowed to react with respectively 2 and 4 eq. silver nitrate. Complexes 2 and 3 catalysed the autoxidation of cyclohexene. They transfer the oxygens of their nitrato groups to phosphines. Complex 3 has been characterized by single crystal X-ray diffraction. The bite of the OPPh 2 py ligand repels the presence of the chlorine atom in the Fe(NO 3 ) 2 plane of 3 which influences the geometric features of the nitrato groups, their oxygen transfer ability.

Reactivity of a (FeNO)-(FeNO3) system in the presence of a ferrocene-ferricinium group tethered nearby via a ferrocenyl phosphine linkage (FcP2) : crystal structures of [{Fe(NO)2Cl}2(μ-FcP2)] and [Fe(NO)2(FcP2)]

Abstract The nitrosyl dimer [{Fe(NO) 2 (Cl) 2 }] ( 1 ) reacts with 1,1′-bis(diphenylphosphino)ferrocene (FcP 2 ) to yield [Fe(NO) 2 (Cl)] 2 (μ-FcP 2 ) ( 2 ), the structure of which has been determined. The FcP 2 moiety bridges two Fe(NO) 2 (Cl) groups symmetrically. Oxygenation of 1 in the presence of FcP 2 yields [Fe(NO 3 ) 2 Cl(O 2 P 2 Fc)] ( 5 ): complex 5 catalyses the autoxidation of cyclohexene. It transfers the oxygen atoms of its nitrato groups to phosphines. When allowed to react with an excess of FcP 2 , 2 gives [Fe(NO) 2 (Fcp 2 )] ( 4 ); the subsequent formation of [Fe(NO)Cl 2 (FcP 2 O)] ( 3 ) is attributed to the reaction of 4 with chlorine liberated in situ. The structure of 4 was also determined.

A fast auto-adaptive method to study the frequency behavior of radiating structures, applied to automatic determination of resonances

Solving electromagnetic scattering and radiation problems with moment methods or finite element methods over a large frequency band gives accurate results, but it is often too time-consuming. So we propose a fast auto-adaptive method to optimize the computational electromagnetics solver applied in the case of various radiating and dielectric structures. This method is able to generate the electromagnetic behavior of the antenna with a very few simulations over a broad frequency band.

Algèbre symbolique appliquée à l'étude des antennes imprimées

Flexible printed-circuit antennas mounted on curved surfaces have recently been applied in mobile telecommunications systems. New simulation techniques are required to handle the complex electromagnetic equations escribing these structures. A novel fast symbolic algorithm as been used in the analysis and synthesis of flexible printed circuit antennas. A number of symbolic objects have been developed to automatically generate the algebraic equations. These are capable of determining electric field and scalar potential for various different exible structures. This paper compares alternative theoretical analysis methods and discusses the model that as been developed.

Powerful algebraic tools for the analysis and synthesis of conformal microstrip antennas

The interest in microstrip antennas printed on arbitrary curved surfaces has increased rapidly, especially for their use in mobile communications. However, their study is always a difficult task. To overcome this problem we propose a theoretical model, which allows their analysis and synthesis. It is based on a fast and accurate symbolic algorithm that automatically generates the solution of complex electromagnetic equations.

Les systèmes de calcul formel appliqués À quelques problèmes d’électromagnétisme

This paper deals with computer algebra systems and explains how these systems are likely to be extremely relevant in addressing electromagnetic problems. After a historical survey, it discusses the various off-the-shelf systems and their features. We suggest how given problems can be formalized and analysed using symbolic algebra systems. Several applied examples are given, with an important bibliography. We study the flat and conformai microstrip antennas : Green’s functions, solutions of the characteristic equations, and so on. We give many informations on the computer algebra systems on the Internet network.RésuméCet article présente les systèmes de calcul formel et explique de quelle manière ils peuvent être d’un grand intérêt pour résoudre des problèmes électromagnétiques. Après avoir traité des aspects historiques, les différents systèmes disponibles sur le marché avec leurs caractéristiques sont présentés. Pour un problème donné, des indications pour le formaliser et organiser le logiciel symbolique sont données ainsi que de nombreux exemples d’application et une bibliographie importante relative au sujet. Le cas des antennes imprimées planes et conformées : fonctions de Green, solutions des équations caractéristiques, etc. est proposé ainsi que de nombreuses sources d’informations sur les systèmes de calcul formel, comme par exemple les serveurs accessibles par Internet.Cet article presente les systemes de calcul formel et explique de quelle maniere ils peuvent etre d’un grand interet pour resoudre des problemes electromagnetiques. Apres avoir traite des aspects historiques, les differents systemes disponibles sur le marche avec leurs caracteristiques sont presentes. Pour un probleme donne, des indications pour le formaliser et organiser le logiciel symbolique sont donnees ainsi que de nombreux exemples d’application et une bibliographie importante relative au sujet. Le cas des antennes imprimees planes et conformees : fonctions de Green, solutions des equations caracteristiques, etc. est propose ainsi que de nombreuses sources d’informations sur les systemes de calcul formel, comme par exemple les serveurs accessibles par Internet.

Accurate Synthesis Model for Microstrip Antennas with Automatic Choice of the Shape Versus Physical and Geometrical Criteria

An accurate synthesis model applied to multilayer probe-fed microstrip antennas, is presented. An appropriate and original use of a symbolic algebra system and a modified Wolff cavity model allow to obtain, with a low computing time, the optimal size and the shape of the antenna, with its uncertainty, versus the physical and geometrical parameters, necessary to a good approach. The numerical and experimental results for different synthesis are shown and discussed.

Visualisation graphique de la propagation des ondes assistée par ordinateur

AnalyseL’une des difficultés rencontrées lors de l’étude de phénomènes de propagation et de diffraction à l’aide de méthodes numériques est, outre la méthode elle-même, l’exploitation et l’interprétation physique du volume très important de résultats obtenus. On propose une visualisation graphique permettant de présenter de tels résultats sous une forme claire et facile à interpréter.AbstractOn studies of propagation and scattering phenomena by numerical methods, one of the difficulties encountered is the physical interpretation of the great number of numerical values obtained. A clear and easy interpretation of such results is presented here, by using graphic techniques.

Diffraction d’ondes acoustiques de surface sur divers substrats présentant des discontinuités a 90ℴ

RésuméLes auteurs présentent une méthode numérique, basée sur les différences finies, permettant de caractériser le comportement d’une onde acoustique de surface au voisinage d’une ou plusieurs discontinuités. L’application de cette méthode à l’étude de la diffraction d’une onde de Rayleigh sur une arête à 90°permet d’obtenir les caractéristiques des modes diffractés, en fonction des constantes élastiques du substrat. Des vérifications expérimentales sont effectuées à l’aide d’une sonde interférométrique. Les résultats ainsi obtenus sont comparés aux résultats théoriques.