Application of the FDTD method to determine complex permittivity of dielectric materials at microwave frequencies using a rectangular waveguide

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 Teflon and Plexiglass measured at the microwave frequencies are presented. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1964–1968, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22611