Wide-band EM characterization of a Ni-Zn ferrite tile in a TEM structure

This paper presents an original wide-band method (from 1 MHz to 1 GHz in the paper) for the electromagnetic (EM) characterization of a Ni-Zn ferrite tile. The method requires the S-parameter measurements of a TEM structure (a stripline cell in this paper) without and with the sample under test (SUT). In parallel, the experiment is faithfully reproduced by simulation through the FDTD method for both cases. This enables to determine the electromagnetic properties of the SUT by adjusting its properties in simulation in order to match the measured S-parameters of the stripline cell thanks to an optimization process. The main advantage of the proposed method lies in the fact that no machining process of the sample is required provided that 1) the size of the sample enables to insert it within the stripline structure, 2) the position of the SUT in the propagating device is known accurately and 3) the insertion of the SUT sufficiently modifies the S-parameters of the TEM structure. Experimental results obtained on a ferrite tile are provided showing excellent agreements with results given in the literature.