Measurement of permeability of oriented Y-type hexaferrites

There is a need to develop high μ materials at microwave frequencies. In the past we were able to prepare by special techniques hard magnetic materials such as Y-type hexaferrites into soft magnetic materials. In this paper, we show results of a measurement technique to measure μ as a function of frequency on these materials. Using a thru-line-reflect calibration technique and a HP 8510B network analyzer we measured S21, transmission coefficient of microstrip line, to deduce the permeability as a function of frequency of oriented Y-type hexaferrites. The microstripline measurements were consistent with microwave cavity measurements at one frequency. The real part of the permeability was constant and equal to 3-4 from 0.5 to 6 GHz with minimal measured magnetic loss tangents. Higher values of permeability may be possible with thinner samples