Fabrice Tristant

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.

Using Transfer Function Calculation and Extrapolation to Improve the Efficiency of the Finite-Difference Time-Domain Method at Low Frequencies

The finite-difference time-domain method (FDTD) needs a long computation time to solve low-frequency (LF) problems. In this paper, we suggest a new way to improve the efficiency of the FDTD method, especially for LF problems such as lightning indirect effects studies. The procedure consists in first calculating the systems response to a quasi-impulse excitation. The quasi-impulse response is extrapolated using the matrix pencil method in order to obtain a totally damped waveform. Next, the systems transfer function is calculated and the response to any excitation is deduced. Thus, this method allows for solving problems with a slow response. For instance, the tool is used to calculate currents induced on wires inside a composite aircraft struck by lightning. Very good agreements with FDTD complete simulations are found. Furthermore, the method allows an important computation time saving.

A numerical tool to estimate lightning indirect effects on a composite aircraft

Nowadays, with the increasing use of composite materials, lightning indirect effects on aircraft are an important problem of interest. Currents and voltages induced by the lightning strike can perturb the equipment working. The purpose of this study is to develop a numerical tool allowing the estimation of current coupling on wires involved by the lightning strike. The model permits to consider several thousands of wires and is a powerful and useful tool, assisting the aircraft manufacturer in the certification process.

A method to decrease computation time of FDTD calculations for low frequency excitations

In this paper, we propose a new way to decrease computation time of the Finite Difference Time Domain (FDTD) method. We focus on signals presenting a very large damping time such as bi-exponential waveforms. The procedure consists first in calculating the transfer function of the system from its quasi-impulse response. Next, based on this transfer function, the response to any excitation (particularly low frequency ones) is calculated. The quasi-impulse response can also be extrapolated using the Matrix Pencil method in order to obtain a waveform totally damped. In any case, very good agreements with FDTD complete simulations are found.

Influence of apertures on the electromagnetic field behaviour within aeronautical metallic halls used as reverberation chambers

This work aims to study the hypothesis to use an aeronautical metallic hall as a mode-stirred reverberation chambers in aeronautics. Consequently, the effect of the apertures of the halls is analyzed from experimental and numerical results. In particular, the objective is to study the ability of such a facility to generate an electromagnetic environment equivalent to a reverberation chamber, to obtain a sufficient number of mode stirrer independent positions and to sufficiently store the energy despite the presence of apertures.