Modelling of electrical properties of Mn-Zn ferrites taking into account the frequency of the occurrence of the dimensional resonance

Teodora Plamenova Todorova – Vencislav Cekov Valchev – Alex Van den Bossche

   Besides their magnetic properties, Mn-Zn ferrites are also characterized by appreciable electrical properties. This electromagnetic nature of Mn-Zn ferrites’ material properties causes a dimensional resonance to occur in samples. The latter hinders measurements of the frequency dependences of intrinsic permittivity and electrical conductivity. In the paper, we present a sign in measurement results that shows the frequency range in which dimensional resonance has already occurred. Above this range, properties extracted from measurements are not intrinsic any longer. We refer to the sign to determine the last point of the measurement data set that is used as an input for an equivalent circuit modelling of the electrical properties. This "last point" criterion helps to exclude the possibility of modelling apparent properties instead of intrinsic ones. The results obtained show that the frequency dependent electrical properties may be well modeled even if the upper limit of the input frequency range to the curve fitting is below the frequency range in which the dimensional resonance occurs.

Keywords: Mn-Zn ferrite, dimensional resonance, electrical conductivity, relative permittivity, ferrite core modelling, equivalent electrical circuit modelling, N87, N97

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