Permittivity measurement using slotted coaxial resonator

We present a method of dielectric permittivity measurement based on a slotted coaxial resonator. The method is applicable at decimeter wavelengths. The resonator is 15 cm in diameter and provides adequate measurement of materials with inhomogeneities up to several millimeters in size. A sheet sample is inserted into a through slot cut in the frame of the resonator. We introduce an approach to data processing exploiting Lorentz´s lemma and present a simple equation that allows for the slot and is valid in the case of an optically thin sample. The experimental study validates the high precision of the measurement. The method can be applied in fundamental investigations as well as in industrial non-destructive testing of sheet materials