Experimental analysis of short-circuit line technique for measuring permeability of ferromagnetic materials

Measurement of S-parameters in order to determine permeability and permittivity of materials is a well-established method, which has already been analyzed in great detail. However, the focus of the analysis has been the permittivity of dielectric materials. We have analyzed experimentally the short-circuit line technique for the determination of the permeability of ferrimagnetic materials, especially in the vicinity of ferromagnetic resonance where the material has high magnetic losses. We analyzed the fact that, by using samples with different lengths, we obtained different values for permeability and evaluated the difference as a function of sample length. Further, we compared the results obtained by single-sample and two-sample techniques and evaluated the influence of the distance between the sample and short circuit. The results were compared with the uncertainties due to measurement errors (sample length, sample position, reference plane position). We have analyzed sintered ferrite materials and also compared the inevitable variability of the samples' permeability characteristics.