Equivalent Circuit Synthesis of Plant Cell Vacuole by Fitting on 2-3 GHz Resonant Frequencies

Abstract

The reflective S-parameters S11 of pure water and five plants of pear, tomato, carrot, ginger, and potato, representing fruits, vegetables, and root vegetables, were measured using a highly sensitive five-pin SMA probe, five times higher than an open-end SMA probe, and the admittance curves were plotted on a Smith chart. The cell vacuole was extracted by grinding and filtering through a 20-micron filter. A specific circle feature and resonant frequencies were observed at high frequencies above 2 GHz in the admittance curve over a frequency range of 1 to 4000 MHz. Equivalent circuits were synthesized using curve fitting on strict values of serial and parallel resonant frequencies when the susceptance, jB, equals zero, and the circuit element values of C, R, and L were determined. The values of the elements were related to the polar molecule H₂O, K ions, and SMA probe configuration. The simulated and calculated values of admittance, circuit elements, and resonant frequencies, determined using synthesized equivalent circuits and derived equations, are consistent with the measured values. Since the cell vacuole substantially consists of polar molecule H₂O and K ion, and the NaCl solution consists of H₂O and Na and Cl ions, the strict value of the NaCl solution can be used as a reference for the admittance value of the cell vacuole.