Broadband Permittivity and Permeability Extraction of Ferrite Cores up to the GHz Range via Measurements and Simulations

摘要

In this contribution a method is presented which allows for the characterization of the magnetic (mu'-j mu'') as well as the dielectric (epsilon'-j epsilon'') properties of ferrites in a broad frequency band (kHz to GHz). In order to determine the material properties at certain frequencies, the simulation model parameters of a particular test setup are tuned via optimization such that the simulated response of a sample to an electromagnetic excitation matches to the measured one. A loop and parallel plate setup support a low frequency parameter extraction of the sample while a coplanar line is used for high frequencies. The extracted material properties are fitted by a broadband causal fit in order to obtain a material model for the whole frequency range. The presented method is verified for a setup with a coil and a ferrite core. The results show that dielectric properties of the ferrite core cannot be neglected for microwave frequencies.