Application of the FDTD method to determine complex permittivity of dielectric materials at microwave frequencies using a rectangular waveguide
Résumé
A new measurement technique is presented to determine the complex permittivity of a dielectric material. The dielectric sample is loaded in a short-circuited rectangular waveguide. The reflection coefficient of the waveguide is measured by Network analyzer and calculated as a function of the complex permittivity using finite difference time domain method (FDTD). The Newton-Raphson method is then used to determine complex permittivity by matching the calculated value with the measured value. A comparison of determined values of the dielectric constant obtained from the Nicholson-Ross technique and the FDTD method is presented. Numerical resultants for complex permittivity of Tefion and Plexiglass measured at the microwave frequencies are presented.