The numerical analysis of a gradiometric coil arrangement has been performed and the response of a metallic material in the vicinity of the coil system has been examined. The system has been excited by a bandwidth limited step function, thus the step response of the different target materials can be measured on the gradiometer. The 3D numerical model has been prepared in the CST EM Studio environment and has been solved by the finite element method. The simulations have been executed for different target materials, i.e. aluminum, steel, stainless steel and in order to unveil the specific contribution of the magnetic permeability and the electric conductivity to the step response for four fictive materials. The results show that the step response is an appropriate parameter to distinguish between the target materials and to provide information about the sensor to target distance.
A computer controlled measurement system based on National Instruments Data Acquisiton card and National Insturments LabVIEW software package has been built. First, the hysteresis characteristics of the tested specimen have been simulated by Jiles-Atherton model, and simulated measurements have been performed using LabVIEW functions. This work is a preliminary study of LabVIEW and the measurement of hysteresis. The main goal is to control the magnetic flux density measured on a toroidal shaped core with a feedback controller. In this paper, the developed procedure, which is able to measure the hysteresis characteristics applying analogue and digital integrators, and to control the waveform of magnetic flux density determined from the voltage induced in the secondary coil wound on the toroidal shaped core is presented. The experience proves that the developed controller is stable and robust. This work is an initial step of the vector hysteresis measurement system.
The design of inductors is not an easy and cheap task considering the dimensions, the nominal value of inductance, the quality factor and the impedance of the component. Before the beginning of manufacturing a new type of inductors, a lot of trial components have to produce, have to measure and have to try out. Finite element modeling is a well-tried process to examine engineering products before manufacturing them. To reduce the cost and the time of the design process, in the paper a finite element model has been built up to simulate inductors. In the paper the model is presented, which is able to simulate the important attributes of the component, for example the inductance, the impedance and the quality factor. The comparison of the experimental and the simulated attributes of the inductor will also be shown. By using the built up model the development possibilities of the inductor have been examined through the modification of the winding.
Koch curve based dipole antennas have been built up, have been simulated and measured to examine the reachable size reduction.The simulations have been performed by the method of moments (MoM) and the results have been checked by the finite element method (FEM) and by measurements. The Pocklington’ integral equation has been implemented in MATLAB environment to simulate the input impedance of dipole antennas. The ATW EFIE method has been implemented and solved by the 4NEC2 software to examine the behavior of arbitrary shaped thin wire antennas. In COMSOL Multiphysics software environment a finite element model has been set up to solve the Helmholtz equation and to simulate the antennas under examination. Koch curve based dipole antennas have been measured in a full anechoic chamber, as well and finally the numerical and the experimental results have been compared.