A Broadband Stripline Technique for Characterizing Relative Permittivity and Permeability

We present a stripline design and calibration method allowing the extraction of relative permittivity of single dielectric samples in the 200-MHz-50-GHz range. The simultaneous extraction of relative permittivity and permeability is also illustrated by characterizing a set of samples comprising magnetic inclusions over the same frequency range. The calibration method involves the use of seven measurements of the stripline scattering parameters (S-parameters) with different length shorts inserted. From these measurements, it is possible to determine the reflections at the transition regions of the stripline to correct the measured S-parameters for characterization. By quantifying a range of samples with increasing percentage volume filling of barium titanate in polyurethane for the case of dielectric samples, and carbonyl iron powder for magnetic samples, this paper demonstrates a reliable method for the broadband characterization of composite materials.