Dielectric Measurement in Liquids Using an Estimation Equation without Short Termination via the Cut-Off Circular Waveguide Reflection Method


IEICE TRANSACTIONS on Electronics   Vol.E101-C   No.8   pp.627-636
Publication Date: 2018/08/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E101.C.627
Type of Manuscript: Special Section PAPER (Special Section on Recent Advances in Simulation Techniques and Their Applications for Electronics)
dielectric measurement,  liquid,  cut-off circular waveguide,  coaxial line,  electromagnetic analysis,  

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In this study, a theory for estimating the dielectric properties for unknown materials from three reference materials without using a short condition was developed. Specifically, the relationships linking the S parameter, electrostatic capacity, the measurement instrument and the jig were determined for four equivalent circuits with three reference materials and an unknown material inserted into the jig. An equation for estimation of complex permittivity from three reference materials without short termination was thus derived. The formula's accuracy was then numerically verified for cases in which values indicating the dielectric properties of the reference materials and the actual material differed significantly, thereby verifying the effectiveness of the proposed method. Next, it was also found that dielectric constant could be correctly determined even when the observation plane was moved to the SOL calibration plane on the generator side. The dielectric properties of various liquids in the 0.50, 1.0 and 2.5 GHz bands as measured using the proposed method were then compared with corresponding conventional-method values. Finally, the validity of the proposed method was also indicated by measurement values showing the frequency characteristics of dielectric properties at frequencies ranging from 0.50 to 3.0 GHz.