Measurement of two-layer medium dielectric property using a novel parameters model in radio frequency

The RLCG parameters model and one-port measurement model of the closed-double ring electrodes have been established to obtain the dielectric properties of two-layer medium in radio frequency. The accuracy of these models was verified by electromagnetic simulation experiments and the permittivity measurement experiments under 160 MHz. Results showed that (1) When the medium dielectric constant epsilon r is an element of 6.03,78.8$$ {\boldsymbol{\varepsilon}}_{\boldsymbol{r}}\mathbf{\in}\left[\mathbf{6.03},\mathbf{78.8}\right] $$, the calculation values based on the models and the real values, have a determination coefficient Rspc2=0.98$$ {\boldsymbol{R}}_{\boldsymbol{spc}}<^>{\mathbf{2}}=\mathbf{0.98} $$ using the quadratic regression function fitting; (2) the effective sensing depth of the ring electrodes was about the structural wavelength of the ring electrodes; (3) the measuring permittivity of the intact mature corn ear were in good agreement with the results in the literatures. This study demonstrates a practical technique to extract the permittivity of two-layer medium with the ring electrodes, and will provide a new way to in situ monitoring the physiological changes of two-layer medium and environmental parameters.