Further Study on Coaxial-Probe-Based Two-Thickness-Method for Nondestructive and Broadband Measurement of Complex EM-parameters of Absorbing Material

Two-Thickness-Method (TTM) based on an open-ended coaxial probe was investigated with an emphasis on uncertainty analysis to perfect this technique. Uncertainty equations in differential forms are established for the simultaneous measurement of complex electromagnetic (EM) parameters in the systematical consideration of various error factors in measurement. Worst-case differential uncertainty equations were defined while the implicit partial derivation techniques were used to find the coefficients in formulation. The relations between the uncertainties and test sample’s thicknesses were depicted via 3D figures, while the influence of the coaxial line’s dimension on the measurement accuracy is also included based on the same analysis method. The comparisons between the measured errors and theoretical uncertainty prediction are given for several samples, which validate the effectiveness of our analysis. key words: coaxial probe, two-thickness-method, absorbing material, EMparameters, permittivity, permeability, uncertainty