Wideband Reference-Plane Invariant Method for Measuring Electromagnetic Parameters of Materials

This paper presents a simple and effective wideband method for the\ndetermination of material properties, such as the complex index of refraction\nand the complex permittivity and permeability. The method is explicit\n(non-iterative) and reference-plane invariant: it uses a certain combination of\nscattering parameters in conjunction with group-velocity data. This technique\ncan be used to characterize both dielectric and magnetic materials. The\nproposed method is verified experimentally within a frequency range between 2\nto 18 GHz on polytetrafluoroethylene and polyvinylchloride samples. A\ncomprehensive error and stability analysis reveals that, similar to other\nmethods based on transmission/reflection measurement, the uncertainties are\nlarger at low frequencies and at the Fabry-Perot resonances.\n