Marco Klingler

EXTENSION OF THE TRANSMISSION LINE THEORY APPLICATION WITH MODIFIED ENHANCED PER- UNIT-LENGTH PARAMETERS

This paper introduces a modifled enhanced transmission- line theory to account for higher-order modes while using a standard transmission line equation solver or equivalently a Baum, Liu and Tesche (BLT) equation solver. The complex per-unit-length parameters as deflned by Nitsch etal. are flrst cast into an appropriate per-unit- length resistance, inductance, capacitance and conductance (RLCG) form. Besides, these per-unit-length parameters are modifled to account for radiation losses with reasonable approximations. This modiflcation is introduced by an additional per-unit-length resistance. The reason and explanations for this parameter are provided. Results obtained with this new formalism are comparable to those obtained using an electromagnetic full-wave solver, thus extending the capability of conventional transmission line solvers.

Modeling Methodology of Automotive Electronic Equipment Assessed on a Realistic Subsystem

Conducted disturbances induced into automotive electronic equipment can be predicted in the early design phase by numerical simulation. This supposes a realistic modeling of the cable harness, as well as the electronic equipment. This paper evaluates a modeling method by the results obtained on a realistic automotive subsystem. The latter is composed of two pieces of electronic equipment connected to each other by a cable harness. This test case was performed on printed circuit boards (PCBs) with full or partial ground planes and using a representative sample of harnesses. Simulation results are compared with measurement results using multiple cable harness samples. A good agreement between measurement and simulation can be obtained for PCBs with full ground plane, provided that fringing effects of the electronic components are taken into account in the equipment model.

Analysis of electromagnetic resonances in the case of a vehicle using different sets of field points

In order to improve the electric/electronic architecture of a vehicle, resonances should be identified and solved upstream. In this paper, we present a study of the resonances occurring inside a vehicle using a numerical code based on the Method of Moments. Three different types of sets of field points have been used to carry out this study. The first set is composed of points localized in the entire volume of passenger compartment. Points at the location of several pieces of equipment constitute the second set. The third set is made up of points along the route of the harnesses. The methodology used for this investigation is based on the computation of the electromagnetic fields on the different sets of field points, followed by the identification of the resonant frequencies by post-processing the field values. An analysis of these results shows that it is possible to study resonance occurring inside the vehicle using only the two first sets of field points, allowing the identification upstream of immunity risks to external sources.

Influence of car body materials on the common-mode current and radiated emissions induced by automotive shielded cables

In order to reduce the radiated emissions due to high power converters in electric and hybrid vehicles, shielded cables are systematically used. This paper presents measurement results of the common-mode current and the radiated magnetic field produced by a shielded cable when different car body materials are considered. A simple but sufficiently representative measurement setup has been defined and constructed to take into account the impact of the new materials considered in automotive industry, such as low conductive carbon fiber reinforced epoxy. The results obtained allow evaluating the magnetic field produced between 10 kHz and 10 MHz when the shielded cable is either inside or outside the car body.

Some limiting aspects of transmission line theory and possible improvements

Wiring still supports most of electric power fluxes as well as data transmission in various infrastructures and transport systems. Hopefully, transmission line theory is a very helpful approximation to estimate interference propagation among cable harnesses. This is definitely a useful tool for engineers, since it enables anticipating the probability of failure of equipment they are connected to. Everything has been written from the initial roots of transmission line derivation, dated from the ancient telegraphists equations established by O. Heaviside back to...1880! until the last developments of sophisticated and off-the-shelf transmission line solvers for complex arrangements of cable networks. The fact is, that these tools are so familiar to many EMC engineers that it might come with some misunderstanding of some results. In this paper, we take a look at the root assumptions of this approximate theory and examine some of its potential weaknesses, through simple examples. Then, we investigate the question of the possible improvement of the classical transmission line theory (when and if required). In principle, this would require the derivation of some kind of generalized transmission line theory or even the examination of the super theory of transmission lines. We rather show that a much more simple modification of transmission line equations is possible for a better approximation of the experimental observations.

Electromagnetic Resonances in Complex Structures: Case of a Vehicle

In this paper, a study of the resonances occurring inside a vehicle has been carried out. The methodology used for this investigation is described in this paper. It consists in two main parts. Firstly, electromagnetic fields are computed in the vehicle using a numerical code based on the Method of Moments. The frequencies of the resonances are then identified by post-processing the computed results. The second part consists in the localization of the resonances inside the vehicle, which provides sometimes enough information to identify and explain their origins.

Device for adjusting electromagnetic losses inside a reverberation chamber application to automotive wireless environment simulations

In this paper, we describe how we can finely adjust the electromagnetic losses inside a mode-stirred reverberation chamber (MSRC) using a device containing a variable quantity of conductive liquid. This device can be used for several applications such as decreasing the lowest usable frequency in MSRCs for ElectroMagnetic Compatibility (EMC) tests or, controlling the RMS Delay Spread inside a configured MSRC to reproduce the wireless multipath channel of different ElectroMagnetic (EM) environments such as those inside vehicles. In this work, we will focus on wireless environment simulation applications. The RMS Delay Spread is determined inside a cavity provided with apertures and loaded with a conductive liquid. It is compared to the one obtained inside an automotive vehicle for different positions of a couple of wireless communication antennas. The comparisons show that, in our case, the static wireless multipath channel of a complex EM environment of a vehicle may be simulated inside such a cavity.

Evaluation of a surface equivalent model in the case of conductive reinforced composite sheets by the use of a macro-fiber modeling approach

This work is focused on the modeling of low conductive and inhomogeneous composite materials. In a first part, based on the assumption that the conductivity of a woven carbon fiber reinforced epoxy material is negligible in the laminating direction (between the stratums), its reinforcement stratum is modeled by the use of a surface equivalent impedance model. This model is then evaluated, in the case of such conductive composite materials, using a macro-fiber model. These two modeling approaches are compared between each other by analyzing the response (current densities) of the reinforcement stratum to an electromagnetic incident plane wave excitation. In the second part of this paper, we use the macro-fiber and the surface impedance models to study the electrical behavior (current follow and anisotropy) of the reinforcement stratum in the case of a plate representing a part of a vehicle chassis partially constituted of this conductive carbon reinforced composite material.

A method to convert scattering parameters from common mode to differential mode for automotive applications

This communication proposes a new method to evaluate the differential mode scattering parameters of cable harnesses from the scattering parameters calculated or obtained conventionally in common mode. Considering a reference conductor instead of a ground plane, the characterization of coupling effects by means of differential mode S-parameters is of great practical interest in automotive applications. In order to show the efficiency of the method, an example of crosstalk prediction is provided.