The planar metal particles, consisting of a multi-turn spirals, are studied with the aim of using them to realize high impedance surfaces or as an elementary cell to create an artificial material. These spirals present a resonant behaviour in a certain frequency band. To obtain miniature devices, a compromise between the surface and the efficiency of the resonance must be found. The compactness of the particles can be increased by using s spirals. However, the accuracy on resonant frequency of existing models is not sufficient for our applications. We present a simple analytical model that determines the resonant frequency from the geometric dimensions of the approximated model. This model is verified by electromagnetic simulations and by measurements.
Abstract.In the field of electronics, the increase of operating temperatures is a major industrial and scientific challenge because it allows reducing mass and volume of components especially in the aeronautic domain. So minimizing our components reduce masses and the use of cooling systems. For that, the behaviours and interface stresses of our components (in particular magnetic inductors and transformers) that are constituted of one magnetic layer (YIG) or an alumina substrate (Al 2 O 3 ) representing the substrate and a thin copper film are studied at high temperature (200°C). COMSOL Multiphysics is used to simulate our work and to validate our measurements results. In this paper, we will present stresses results according to the geometrical copper parameters necessary for the component fabrication. Results show that stresses increase with temperature and copper's thickness while remaining always lower than 200MPa which is the rupture stress value.
The paper takes into consideration the inductive transducers with magnetic fluids for inclination and aerodynamic measurements. Using their functional principle, we built flow rate transducers and flow meters for gases. In a N+1 flow meters network for gases controlled by computer, every N flow meters of closed range are supervised by another flow meter of higher range. The software of this structure can warn about any gases leakage in the network. Starting from the characteristics of the magnetic fluids transducers, the paper investigates the influence of the sensors reply time to the accuracy of measurements and to the possibility of detecting the gases leakage in the network.
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