Dielectric measurement of liquids in 1GHz band based on comparison with reference materials using an open-ended cut-off circular waveguide

In this paper, the measurement frequency band was extended from 1.0 to 2.0 GHz in the method of measuring the dielectric properties in liquids based on comparison with reference materials. For that purpose, the interpolation formula was expanded to 11 points based on a combination of the method previously proposed by the author. In this case, a comparative expression to the reference material was applied to the coaxial feed type open-ended cut-off circular waveguide reflection method for the purpose of easily and instantaneously measurement of the dielectric properties. Moreover, S 11 values were calculated via electromagnetic analysis for individual jig structure conditions and dielectric property values without actual S 11 measurement under the condition that the tip of the measurement jig with open, short-ended conditions and with the test material inserted. The following investigation was carried out in order to confirm the effectiveness of the proposed method. The accuracy of the estimation formula was first theoretically and experimentally verified at 2.0 GHz for cases in which values indicating the dielectric properties of the reference material and the actual material differed. We also confirmed that the dielectric properties of liquid can be measured using an open-ended cut-off circular waveguide more simply and instantaneously than the conventional method even in the continuous frequency range from several limited discrete frequency data.