S₁₁ Calibration of Cut-Off Circular Waveguide with Three Materials and Related Application to Dielectric Measurement for Liquids

抄録

A method for the calibration of S₁₁ at the front surface of a material for a coaxial-feed type cut-off circular waveguide with three reference materials inserted and no short termination condition was proposed as a preliminary step for dielectric measurement in liquids. The equations for jig calibration of S₁₁ with these reference materials were first defined, and the electrostatic capacitance for the analytical model unique to the jig was quantified by substituting the reflection constant (calculated at frequencies of 0.50, 1.5 and 3.0 GHz using the mode-matching (MM) technique) into the equivalent circuit, assuming the sample liquid in the jig. The accuracy of S₁₁ measured using the proposed method was then verified. S₁₁ for the front surface of the sample material was also measured with various liquids in the jig after calibration, and the dielectric constants of the liquids were estimated as an inverse problem based on comparison of S₁₁ calculated from an analytical model using EM analysis via the MM technique with the measured S₁₁ values described above. The effectiveness of the proposed S₁₁ calibration method was verified by comparison with dielectric constants estimated after S₁₁ SOM (short, open and reference material) calibration and similar, with results showing favorable agreement with each method.