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International audience; In wireless communication, channel propagation prediction is sometimes difficult especially in confined metallic space due to the fast fading and multipath complexity. Wireless system deployment on aircraft and other vehicles seems to be nowadays unavoidable but some concerns remain about the reliability and security of critical and real-time communications. This paper presents the opportunity given by the Mode Stirrer reverberating Chamber (MSRC) to develop and test a wireless communication system in a multipath propagation environment. The controllable and repeatable statistical characteristics of a MSRC studied here by the measurement of transfer functions (TF) in the frequency domain make it possible to define and also emulate Rayleigh propagation channel. Modified Q factor by loading the cavity can change the RMS delay spread and the canal selectivity in order to reproduce representative propagation paths, as the one measured in an aircraft.

This paper addresses the question of modelling voltage source terms when applying Agrawal's Field-to-transmission Line model in a numerical procedure involving a 3D full wave solver and Multiconductor Transmission-line Network solver based on the BLT equation. It particularly stresses the fact that the prima facie model consisting in integrating voltage sources along cells larger than usual criterion of λ/10 is not valid for some conditions of terminal loads of the transmission-line. Low frequency applications of simple lines in short-circuit/open circuit allow analytical analysis of the problem. This is a reason why a unified model of equivalent sources is developed here for any type of load conditions and for low frequency applications. Different validations have been carried out applying the CRIPTE code and various illustrations are presented.

Wireless systems used in confined environment show sometimes some operating instabilities essentially due to the propagation channel. In order to predict and improve the wireless link performances, we propose to test the wireless system in a controlled propagation channel. As shown in this paper, mode stirred reverberating chambers seems to be an interesting mean able to simulate realistic and reproducible channels even with Rayleigh distributed fast fading channel. An experiment consisting in measuring Transfer Function between two antennas in multi cavities was carried out and driven by WIFI connection; results present the WIFI link integrity emulated by multipath channel propagation and controlled with simple physical cavity characteristics (Q-factor, delay spread, stirrer position, etc.).

An entire set of high-intensity radiated field transfer functions including the main types of contemporary test methods is presented. Consequently, the applied frequency range for this task expands over many decades, from the kilohertz range up to 40 GHz. A major aim is to demonstrate the application of numerical computer modeling for such a task. Results of measurements and various solvers are compared to each other. As the activity serves also for the validation of such applications, the scenario is investigated by the use of a fuselage model with limited complexity.

International audience; This paper deals with the modeling issue of the nearfield coupling of an unshielded twisted-wire pair on a nearby single wire. It introduces a discussion about the appropriate modeling method for predicting the induced current on the victim wire and proposes a cost-effective approach to deal with either ideal or nonideal twisted pair. A nonideal twisted pair consists of a twisted pair whose ends are left untwisted for connection to equipment. We show that the current distribution may follow a specific spatial distribution on the nearby wire. These coupling effects are evidenced through the analysis of an equivalent circuit under the low-frequency assumption. These behaviors are illustrated for the case of both an ideal twisted pair and a nonideal twisted pair. For the latter, the ideal bifilar helix may be modeled by a simple equivalent model bifilar cable.

International audience; This paper focuses on experimental measurement of power and signal transfer of wireless communication in reverberating cavities. The experiment is based on the evaluation of a transfer function between two antennas placed inside and outside a confined reverberating environment made of several metallic cavities. Inside these cavities, a WIFI communication is used in order to control the measurement setup in order to take advantage of its simple connection with the measurement devices. Therefore the first exploitation of this experiment is directly to measure S-parameters as main parameters for characterizing this transfer functions. The second type of exploitation consists in the assessment of the integrity of the WIFI communication in such a closed and confined reverberating environment.

One of the main characteristics of a reverberation chamber is its quality factor since it determines the field enhancement and the decay time of the impulse response. If a receiving antenna is placed in the room, it absorbs part of the energy which leads to a decrease of the intrinsic quality factor of the room. Such a well-known phenomenon is quantified by the quality factor of the receiving antenna, and a simple analytical formula is available in the literature. If the antenna placed in the chamber is a transmitting antenna, it also receives the waves reflected by the chamber walls and it is often supposed that its quality factor is still given by the same formula. However, it has been already outlined that the quality factor of an antenna used either in a transmitting mode or in a receiving mode is not identical, but differ by a factor of two. The objective of this contribution is to propose an analytical approach, based on the statistical properties of scattering matrices, to justify this result. Furthermore, experiments have been carried out both in the frequency domain and in the time domain to clearly point out the increase of the power dissipated in a transmit-mode antenna. Polarization effects are also studied.

In this paper, the possibility of extending the validity range of the transmission line theory in evaluating differential mode signals along two-wire lines above a ground plane is discussed through analysis and simulation. It is shown that, when the above-ground height of the two wires is larger than about twice their separating distance, the calculation of the characteristic impedance of the line can be performed disregarding the presence of the ground. The presented analysis suggests that the validity of the transmission line theory in the evaluation of differential-mode signals is conditioned upon an electrically short distance between the wires, regardless of the height above the ground plane.

This paper addresses the issue of transfer function measurements inside a structure in High Intensity Radiated Fields environment (HIRF). In this context, a simple reference test object was designed and used as a set up verification device to be tested before HIRF measurement campaigns on aircraft. In order to obtain a reference measured transfer function between the incident E-field and an internal induced current this object has been calibrated in laboratory using a strip-line which enables to fully control the incident EM field. We focus, here, on the need to perfectly control the whole measurement links and test setup to ensure a sufficient level of sensitivity and reproducibility.

This paper deals with a network formulation of the power balance approach in order to estimate high frequency coupling mechanisms in complex systems. After giving the general principles of this approach found in the scientific literature, the network development of the method is presented, based on an electromagnetic topology analysis. Finally, the network formulation of this approach is applied on a simple two contiguous cylindrical structure by easily adapting a computer code initially dedicated to electromagnetic topology on cable networks.

In the domain of aeronautics, the future more electric aircraft will have to face a difficult issue related to the increasing number of wires and connectors, impacting on the weight and system reliability. A possible solution for solving at least part of this problem is to introduce power-line communication for specific applications. In this paper, the cabin lighting and communication system has been chosen as an initial scenario. Indeed, the tree-shaped architecture of the cabling is complicated enough to be representative of many other aircraft harness configurations. Channel characteristics are first determined from a propagation model based on the multiwire transmission-line theory. A software tool simulating PLC communication has been developed. By introducing the predicted channel transfer functions of different links into this software, the throughputs that can be reached, taking into account the electromagnetic constraints related to aeronautic standards, are discussed.

This paper focuses on the coupling between a twisted pair cable (TPC), which is modeled as a perfect helix of two conductors, and a single wire. The simulation of the current on a victim wire induced by a TPC made of a single twist gives non-obvious patterns depending on the starting angle of the TPC. An analytical model based on a circuit representation is developed in order to understand these specific current distributions. A coarse simulation of the TPC is first carried out with a minimum number of tubes that exhibits the same behavior as a finely discretized model. Then, the circuit approach applied in this case shows the influence of the arrangement of inductance and capacitance mutual terms along the twisted pair on the distribution of the currents on the nearby wire. It eventually explains the specific role of the starting angle.

This paper proposes a semianalytic solution to the problem of high frequency coupling on a wire running in electrically large enclosures. This model is basically derived from the transmission-line (TL) theory in which the electromagnetic (EM) environment, represented as a random plane-wave spectrum, is characterized by its statistical parameters. The results are compared to those obtained by randomly generating elementary plane-wave samples and numerically calculating their EM coupling through a TL model.

This paper deals with the application of the Power Balance approach to a generic object, the GENEC, to assess high frequency coupling mechanisms. This method has been validated by measurements performed in a reverberation chamber. Finally, it will be shown how this method, once included in a global strategy, can be complementary to “Maxwell Codes” to predict high frequency constraints in a complex system.