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3D Visualization of Numerically Calculated Bearing Error Texture in Disturbed DVOR Scenarios
Sergei Sandmann, Heyno Garbe
Institute of Electrical Engineering and Measurement Technology, Germany
Radio navigation aids like the Doppler Very High Frequency Omnidirectional Radio Ranges (DVOR) are sensitive to scattering objects like buildings and wind turbines. Due to multipath and shadowing effects the propagation of the corresponding "signal in space" is disturbed and deviations of the transmitted navigation content are expected.
Existing analytical and numerical methods to determine the induced bearing error in space are often aimed at estimating just one value for the expected maximum error in a specified space volume or at most provide 2-dimensional observation surfaces, on which the error is represented by color mapping. However, in order to understand the propagation of bearing error in space, a 3-dimensional investigation is essential but often not realizable due to very high computational effort.
In this paper a method is presented to calculate the 3-dimensional texture of the bearing error while constraining computational effort to a reasonable amount.
Fastener Lightning Current Assessment in Aircraft Fuel Tank
Paul Monferran1, Christophe Guiffaut1, Alain Reineix1, Fabian Fustin2, Fabrice Tristant2
1XLIM laboratory, Limoges, France; 2Dassault Aviation Company, Saint-Cloud, France
This paper proposes an approach for the lightning current assessment in an aircraft fuel tank taking into account the variability of the fastener resistance. The electromagnetic fastener model is a wire with a resistance. The uncertainty model is a log-normal probability law established in previous work from a measurement database. Each fastener resistance takes a probabilistic value according to this law. This model is included in a FDTD fuel tank modeling. Several simulations are performed in order to surround the measured currents at various locations of the fuel tank. The results highlight not only the approach validation but also the requirement of the use of an uncertainty model for the lightning current assessment.
Characterization at High Frequencies of Planar Transformers for Aeronautical Converters
Carlos Dominguez-Palacios, Joaquin Bernal, Mariangeles Martín-Prats
University of Seville, Spain
This work presents a quick and simple method to characterize planar transformers at high frequencies. This method only requires two measurements which can be performed with a spectrum analyzer with tracking generator. By performing a circuit analysis of a high-frequency circuit model of the planar transformer regarded as a four-ports device we obtain analytical expressions of the transmission coefficients of the planar transformer excited in open-circuit, common mode and differential mode setups in a wide frequency range.
This allows us to develop an efficient method to determine the high-frequency parameters of the circuit model from the result of these simple measurements. Different commercial planar transformers have been measured and the predicted performance of the model has been compared with measured responses. We have verified that in all the cases the measured transmission coefficient exhibits the behavior predicted by the theoretical analysis.
Imaging electric and magnetic near field of radiating structures by infrared thermography
Daniel Prost1, François Issac1, Maxime Romier2
1ONERA, France; 2CNES, France
The characterization and visualization of the radiated electromagnetic field is a way to diagnose and check microwaves sources, in particular in the space industry. Beyond the traditional 3D scanning of the radiating element, infrared thermography is an alternative way that may give key results in a reduced time, since a few seconds are sufficient to obtain the emitted field map even for a complex multi-cells antenna. This method, called EMIR (ElectroMagnetic InfraRed) has been developed and used for years at ONERA. We have recently extended this technique to the magnetic field, which will lead to a complete characterization of the near field structure. We illustrate this feature in the particular cases of antennas for space application and for a High Impedance Surface (HIS), a metamaterial structure that could be used to reduce the coupling between antennas confined in compact structures (typically size constraints of the spatial components).
A Numerical Analysis of HIRF- and DCI-Equivalence by Characteristic Mode Theory
Jan Ückerseifer1, Martin Aidam2, Markus Rothenhäusler3, Frank Gronwald1
1University of Siegen, Germany; 2Daimler AG, Germany; 3Airbus Defence and Space, Germany
This paper analyzes HIRF- and DCI-excitations of canonical structures regarding their surface current distributions. The latter are numerically computed for various test scenarios and investigated by Characteristic Mode Analysis. Based on the resulting modal decompositions, HIRF induced surface current is expanded in terms of DCI modes with the intention to approximate radiated susceptibility tests by conducted ones. In order to allow existing deviations to be quantified, several metrics judging the equivalence of HIRF- and DCI-excitations are calculated.