Estimation of complex permittivity using rectangular waveguide with flangeby FDTD method

A method for estimating complex permittivity of a material using a rectangu lar waveguide with a flange is presented by the finite difference time doma in (FDTD) method. An advantage of tile present method is that it is not nec essary to vary the material structure in order to insert it into the wavegu ide. Therefore estimation errors related to tile dimensions of the material are almost negligible. In this case, fluoridated rubber is chosen as tile low-loss material. The comparison of the complex permittivity of the materi al determined by the present method with FDTD and the conventional waveguid e method at 10 GHz is performed. It uas confirmed that the present method i s effective for estimating the complex permittivity under tile condition th at the length of tile flange is about 50 mm (1.7 lambda) square.