System and method for quantitative measurements of a material's complex permittivity with use of near-field microwave probes

摘要

A method for measuring a material's complex permittivity is provided where a near-field microwave probe is positioned a predetermined distance from a first and a second standard sample for measuring a relative resonant frequency shift of the near-field microwave probe for standard samples. Based on measurements, calibration coefficients are calculated. A relative resonant frequency shift of the near-field microwave probe for a sample under study is measured by fast frequency sweep technique while the distance between the tip of the probe and the sample under the study is maintained nominally at the distance between the tip of the probe and each standard sample during a calibration procedure by a shear-force based distance control mechanism. Also, the change in the quality factor of the probe for unloaded and loaded resonator is measured. The dielectric constant of the sample under study is calculated using the resonant frequency shift and the change in the quality factor of the near-field microwave probe for the sample under study and the calibration coefficients obtained during the calibration procedure.