The reflectivity discrepancy method for the determination of the permittivity and permeability of complex materials

The possibility of distinguishing whether the losses in a material under investigation are due to either its dielectric or magnetic properties, or both, is tested by treating a single spectrum of a reflection simulated by computer. To determine the frequency bandwidth and range of sample thickness sufficient to measure both the permittivity and the permeability at any frequency, the reflection spectrum of a sample with magnetic and dielectric properties is analyzed. If the reflectivity is measured over a frequency band several times wider than the absorption line of the sample and the sample is semitransparent in the middle of the line, the magnetic and dielectric spectra may be determined. Insertion of an air gap between the sample, and the plane of the short circuit has been found to facilitate the measurements. The validity of this approach is shown with permittivity and permeability measurements; of a composite substance containing iron.