Improved Test Method for Radio Frequency Band Characteristics of Ferrite Magnetic Materials

The complex permeability of magnetic materials at radio frequencies significantly impacts the electromagnetic compatibility characteristics of magnetic components. The precision of its measurement is crucial for the design, selection, and study of electromagnetic compatibility properties of magnetic components. This paper discusses the key material parameters affecting the radio frequency characteristics of magnetic materials and provides a detailed analysis of how these parameters influence the complex permeability of magnetic materials. It reveals why traditional methods for measuring the complex permeability of magnetic materials are not applicable at high frequencies. The paper identifies the parasitic inductance and capacitance in the measurement winding as the primary factors affecting measurement accuracy. Consequently, it proposes a new method for testing the complex permeability of magnetic materials in the radio frequency range, considering the effects of parasitic parameters in the measurement winding. This method effectively combines small-signal measurements with finite element simulation to calibrate parasitic parameters, significantly extending the frequency range of the measurement results. Experimental findings demonstrate that the proposed method accurately extracts the characteristic parameters of magnetic materials in the frequency range of 30 MHz to 1 GHz.