Christophe Guiffaut

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.

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).

A New Conservative High-Order Modified FDTD(2,4) Scheme

In this paper, we propose a new 3-D conservative FDTD(2, 4) scheme exhibiting properties close to the 2-D-M24 scheme. This scheme is designed to retain a 2-D stencil in the field update equations and has high-phase accuracy at low-grid resolutions. Moreover, an accurate Courant-Friedrichs-Lewy condition has been validated for this scheme. Some experiments are conducted to assess the higher accuracy of the proposed scheme.

Modeling of different cables types and their combinations for lightning and HIRF EMC studies in the FDTD method.

This paper presents some recent developments on the thin oblique wire formalism in the FDTD method. This approach allows us to build various models of cables and to include lumped circuit elements while keeping the ability to freely place and incline cables in the FDTD grid. The industrial interest for this versatile approach to handle cables leads to develop MPI algorithm in order to solve EMC problem of aircraft.

Local Crank-Nicolson procedure for short thin wire in the FDTD method

Recently we have introduced a new approach based on the Hollands formalism to deal with thin wire in the FDTD method. However stability problem occurs when a wire has its length very short compared to the FDTD cell size. To avoid CFL criterion reducing, an original procedure using a temporal Crank-Nicolson scheme is proposed. This approach is applied to the auxiliary equations of Hollands formalism only.

Susceptibility of PCBs including non linear elements: A time-domain approach

This paper presents a time-domain approach to address the susceptibility of printed circuit boards (PCBs) including non-linear elements such as on-chip ESD protection devices. The modeling of the boards is performed using a multiconductor transmission lines formalism, and the non linear loads are taken into account using a new SPICE-compatible generic diode model with special emphasis on non linear capacitance and recovery phenomena.

New oblique thin wire formalism in the FDTD method

In the FDTD method, the Cartesian meshing is a critical point for conforming structures and small geometries. For thin wire formalism, one cumulates small section with a problem of conforming to the Yees cell and fast variation of both looping magnetic field and radial electric field close to the wire. Among all previous thin wire published models, only Hollands approach [1] has evolved toward inclined wires. Hence the works of Ledfelt [2] and Edelvik [3] show that it is possible to have a wires behaviour independent of its location in the Yees cell or its obliquity. Our new approach compared to [3] is justified by the necessity to deal with a junction between several oblique wires. Indeed [3] is not extended for multiwire junction because the coupling between the wire current and the electrical field uses a cylinder-shaped stencil with a section superior to the FDTD cell size and so it is too difficult to suit correctly to a junction with more than two wires. To avoid this problem, we propose a technique where the coupling between the wire and the FDTD meshing is limited to only the cells that contain a part of the wire.

Time domain radiating model for GPR antenna

In order to realize the analysis of subsurface constitution by non-destructive detecting methods, one of the best candidates is the GPR (Ground Penetrating Radar). Since some years, it has successfully been used in various applications fields such as in archaeology, geology domains and for civil engineering. More recently, an increasing interest is devoted to the survey of the surface of Mars. We can quote the recent missions Mars Express, Mars Reconnaissance Orbiter and now Aurora. So to discover the history of Mars planet, many missions seek to establish topography of the subsurface. Concerning the ExoMars mission, WISDOM [1] (Water Ice and Subsurface Deposit Information on Mars) consists in a Rover carrying several elements including a GPR. This one contains a radar unit and embedded transmitting and receiving antennas of Vivaldi antennas type [2]and operates in the waveband [0.5 – 3] GHz. In order to prepare the mission and to evaluate the behavior of the antennas, we have to make models of the transmitting antennas mounted on his Rover. The FDTD [3] approach has been chosen for this study. Because it as proven to be one of the most popular techniques reported in the literature to deal with GPR problems. The difference of scale between these two elements arises then. To overcome this problem, it seems unavoidable to establish a representative model of these antennas in their context. To do this, we have developed an electrical dipolar source model coupled to a Huygens surface in the FDTD method.