Alain Reineix

Investigations about the Use of Aeronautical Metallic Halls Containing Apertures as Mode-Stirred Reverberation Chambers

The possibility to use aeronautical metallic halls (AMHs) equipped with a mode stirrer as mode-stirred reverberation chambers (MSRCs) is investigated. The objective is to study the ability of these facilities to generate an electromagnetic environment equivalent to an MSRC in spite of the apertures linking the inner and the outer environment. In particular, the objective is to check if a sufficient number of independent positions of the mode stirrer can be obtained and if the energy storage can be sufficient within these facilities. Encouraging experimental and numerical results, respectively, obtained on a real AMH and calculated with full-wave method on prototype halls are presented and discussed.

Study of electric field radiated by WiFi sources inside an aircraft - 3D computations and real tests

In this paper, the electric field radiated by WiFi sources inside an aircraft is studied. 3D modeling using the FDTD method allows calculation of electric field near punctual locations and on the entire aircrafts surface. The influence of the furniture inside the cabin is also discussed. Measurements in the aircraft (a Dassault Aviation Falcon) are presented. The comparison with real tests demonstrates a rather good concordance with computations.

Axially magnetized circular ferrite microstrip antenna

Theoretical and experimental investigations on a circular ferrite microstrip antenna (FMA), biased axially by a steady magnetic field, are reported. The ferrite medium is partially magnetized to generate good circular polarization. The simple cavity model is used for the analysis of the circular FMA. The resonance condition of the circular FMA is obtained. The magnetic tuning can be understood from this resonance condition. The circularly polarized far fields are derived. The total radiated power and the dielectric, conductor, and magnetic losses are calculated in order to obtain the gain of the circular FMA. The resonant frequency, gain, and circularly polarized radiation pattern, computed theoretically for a circularly FMA, were verified experimentally.<<ETX>>

An estimation of the electrical characteristics of planetary shallow subsurfaces with TAPIR antennas

In the frame of the NETLANDER program, we have developed the Terrestrial And Planetary Investigation by Radar (TAPIR) imaging ground-penetrating radar to explore the Martian subsurface at kilometric depths and search for potential water reservoirs. This instrument which is to operate from a fixed lander is based on a new concept which allows one to image the various underground reflectors by determining the direction of propagation of the reflected waves. The electrical parameters of the shallow subsurface (permittivity and conductivity) need to be known to correctly determine the propagation vector. In addition, these electrical parameters can bring valuable information on the nature of the materials close to the surface. The electric antennas of the radar are 35 m long resistively loaded monopoles that are laid on the ground. Their impedance, measured during a dedicated mode of operation of the radar, depends on the electrical parameters of soil and is used to infer the permittivity and conductivity of the upper layer of the subsurface. This paper presents an experimental and theoretical study of the antenna impedance and shows that the frequency profile of the antenna complex impedance can be used to retrieve the geoelectrical characteristics of the soil. Comparisons between a numerical modeling and in situ measurements have been successfully carried over various soils, showing a very good agreement.

Initial results of the Netlander imaging ground‐penetrating radar operated on the Antarctic Ice Shelf

The objective of the Netlander mission was to land 4 small geophysical stations on the surface of Mars to study the deep interior, subsurface, surface and atmosphere of the planet. Included in the payload was a ground penetrating radar (GPR) designed to retrieve not only the distance but also the direction of the reflectors, thus providing a simplified 3D imaging of the subsurface. In this paper we report initial results obtained during the RANETA campaign on the Antarctic ice shelf. Data from two soundings of the ice-bed rock interface are analyzed, demonstrating the capability of the radar to disentangle echoes from different reflecting facets of the bed rock.

Low-frequency characterization of composite panels from a near-field magnetic shielding effectiveness measurement

This paper presents a simple method allowing to obtain an homogeneous panel model from an inhomogeneous composite panel thanks to a near-field magnetic shielding effectiveness (MSE) measurement in the low frequency range (f <; 1 MHz). The method, which does not require the knowledge of the detailed internal geometry of the panel, consists in determining the “equivalent conductivity” of the homogeneous model. After the validation of the measurement setup on a copper plate of known conductivity, homogenization of 3 different samples is presented. Finally, homogenization of samples made of different inhomogeneous layers previously characterized separately is presented and validated.

Complete Time-Domain Diode Modeling: Application to Off-Chip and On-Chip Protection Devices

Protection elements are commonly used in electronic systems: digital integrated circuits (ICs) include built-in electrostatic discharge protection devices, and sensitive lines or printed circuit boards traces are often protected using discrete elements, such as clamping or Zener diodes. In order to know if a perturbation is able to disturb or damage ICs, the actual level of signal entering the digital core of the components must be accurately determined, taking into account all the effects of the protection devices. Thus, assessing the perturbation signal at IC core level requires accurate models of the protection elements, even in the case they are inactive. Therefore, this paper focuses on the experimental and theoretical evaluation of the protective behaviors and parasitic effects of these elements. Some limitations of the standard SPICE diode and IBIS models are discussed, and a modeling methodology is presented. Based on a time-domain characterization method associated with a parameter-extraction procedure for enhanced SPICE diode models, the methodology is applied to both discrete and on-chip protection devices and has a good agreement with measurement.

Determination of the “quasi-ideal reverberation chamber minimum frequency” according to the mode stirrer geometry

An original method allowing to define from measurements a specific frequency called “Quasi-Ideal Reverberation Chamber Minimum Frequency” (QIRCMF) is presented. This frequency corresponds to the frequency where a mode stirred reverberation chamber starts to work “quasi-ideally”. The method is based on 1) the assessment of the electromagnetic field distributions obtained in the working volume (in comparison with the distributions obtained in the ideal model defined by Hill [1]) and 2) the number of uncorrelated samples obtained over one mode stirrer revolution. Experimental results clearly show that the QIRCMF is reduced by increasing the mode stirrer geometry in particular when the reverberation chamber works at its optimal Q-factor. Original results corresponding to the influence of the mode stirrer geometry on the EM field distributions obtained in the working volume for different Q-factors of the facility are also presented.

New thin coated wire formalism for FDTD method

Recently we have introduced a new approach based on Hollands formalism to deal with then thin oblique wire in the FDTD method. Here we propose an original technique to model a thin wire with surrounding a dielectric sheath accurately. In addition, the multiwire junction of our oblique thin wire formalism has been generalized by using a rigorous equivalent circuit scheme of the coated wire.

Susceptibility of printed circuit boards in complex electromagnetic environment

The susceptibility of printed circuit boards (PCB) in a reverberation chamber can be simulated by using the superposition of random plane waves to obtain the corresponding Hills model. The aim of this work is to avoid simulating the entire reverberation chamber by 3D methods. Magnitudes and resonances measured in RC are compared to FDTD and MTL results with a Hills model of plane waves transposed in the time domain. Then, we use this model to study the susceptibility of the printed circuit board (PCB).