Improvement of impedance spectroscopy methods: resonance analysis of samples

An impedance spectroscopy method, using an Agilent E4991A RF Impedance/Material Analyzer, was employed for the investigation of radiofrequency and microwave dielectric characteristics for some ceramic materials with high dielectric permittivity. Experimental observations recorded single, double and even triple resonances in the permittivity spectra, while for the selected samples significantly different values of permittivity from the ones found in existing literature were directly measured and observed in the frequency range of 100 MHz-1 GHz. The specified material analyzer is designed to work within certain permittivity-frequency domains; working outside these limits leads to significant errors when carrying out direct measurements of permittivity. Having observed that the resonance measurements are not associated with the intrinsic material properties but with the sample resonances, we proposed a dielectric resonance cavity model for sample purposes and we determined the dielectric permittivity at different resonance frequencies. A scaling procedure, based on the computed values of permittivity, was applied in order to correct the directly measured permittivity spectra where the frequency was outside the resonance domains. The corrected data are in good agreement with those measured using other techniques and suggest that the proposed procedure extends the spectroscopy method currently used for high permittivity measurements. The sources of error for the proposed method were investigated.