Complex Permittivity Determination with the Transmission / Reflection Method

The objective of this research is to develop a database on the characterization of civil engineering materials to assess the penetration of electromagnetic waves inside buildings. In particular, GSM waves based on the estimation of the specific absorption rate (SAR).This paper presents a technique to calculate the complex permittivity of dielectric materials. The technique is based on measuring Sij parameters of a rectangular waveguide filled with a sample of material under test and the iterative process of Newton-Raphson. The calculation of the complex relative permittivity can be applied to the Sij parameters measured with and without calibration of Vector Network Analyzer VNA. Two measures in Transmission / Reflection is sufficient to evaluate the complex permittivity of dielectric material, the first measurement with the sample holder empty or filled with a standard dielectric and the second measurement with the sample holder filled with the material to be characterized. The results obtained from samples of dielectric materials (wood, Teflon, plaster and concrete) on the X-band (8.2 - 12.4 GHz) and Ku-band (12.5 - 18 GHz) show the validity of the proposed method.