Evaluation of complex permittivity of materials with deformed cross-section in coaxial line

A broadband measurement method is presented to evaluate the complex permittivity of a deformed sample. Theoretical basis of the method is the hybrid electromagnetic field analysis, i.e, the extended spectral domain approach combined with mode-matching method (ESDMM). The sample is required to have the rotational symmetry but may have the deformation and/or air gap between the sample and the conductor walls of coaxial line, which eases the machining accuracy of sample. The proposed evaluation method is verified by virtual experiments as well as actual measurements.