Determination of Distilled Water Dielectric Constant by 2D-FDTD Method at X-Band Frequencies

This paper presents a new iterative method for estimating the dielectric constant of distilled water using a WR90 shorted rectangular waveguide in the X-band with a hole that facilitates the insertion of water into the waterproof waveguide. The SII parameter at the reference plane as a function of the dielectric constant of each layer is calculated by applying the two-dimensional finite-difference time-domain (2DFDTD) method to the wave equation. The NeIder-Mead algorithm is then applied to estimate the dielectric constant. This is done by comparing the results of SII parameters. This method has been validated on two cases of monolayer and bilayer, such as air and air-plexiglass and plexiglass-distilled water.