Evaluation of complex permittivity of materials partially filled in coaxial line by using hybrid numerical method

An effective evaluation method of complex permittivity in wide microwave frequency range is proposed by using rigorous calculation on partially filled materials in coaxial line. Electromagnetic field analysis for the evaluation is based on extended spectral domain approach combined with mode-matching method (ESDMM). ESDMM is accurate and more efficient than FEM, and suitable for the iterative fitting calculations for the estimation of the material characteristics. Microwave absorbing rubber sheet for material sample was measured by the present method. The sample preparation and setting are far easy compared with conventional method, because the new method does not require filling exactly the whole cross section of coaxial line. The evaluated results by ESDMM have shown good agreement with the values described in technical data sheet.