Modeling and Calibration in Near-Field Microwave Microscopy for Dielectric Constant and Loss Tangent Measurement

Abstract

The characterization of liquid samples using evanescent microwave fields is described. A calibration model is developed to relate the measured near-field reflection coefficient to the local properties of the sample under test. As a demonstration, permittivity extraction of different sodium chloride solutions is experimentally determined. The accuracy of 0.3% and 1.3% is obtained for the dielectric constant and the loss tangent at 2.45 GHz.