Determination of Complex Permittivity of Columnar Materials with Arbitrarily-Shaped Cross Section in Rectangular Waveguide

The extended spectral domain approach combined with the mode-matching method (ESDMM) is applied to analyze the scattering characteristics of lossy dielectric post with arbitrarily-shaped cross section in the rectangular waveguide. ESDMM is accurate and efficient, and it is suitable for the iterative fitting to estimate the material characteristics. An effective evaluation method is proposed for the complex permittivity of the lossy dielectric post placed in the rectangular waveguide based on ESDMM. The sample preparation and setting become much easier than those for the conventional methods. Complex permittivity of lossy dielectric sample with non-rectangular cross section is evaluated by this procedure and the measured results show good agreement with ones measured by conventional method over the X-band.