Normal and oblique incidence free-wave technique for automatic measurement of permittivity and permeability at microwave frequencies

A free-wave method for determining the dielectric and magnetic properties of materials from transmission and reflection measurements made at normal and oblique incidence is proposed. The method combines frequency and time measurements, thus simplifying the experimental set up. The technique searches for the experimental configurations which lead to the least errors from algorithms by taking into consideration angle of incidence, polarization and diffraction. The avoidance of ambiguities is also considered by the method which tries to be general regardless of both frequency and sample thickness. X-band practical realization has been out carried to validate of the technique by comparing the results obtained with those from well-established waveguide techniques at these frequencies. The measurement procedure is fully automated using the HP8510 network analyzer controlled by an HP362 computer which also processes the data.