Microwave measurements of the complex permittivity of construction materials using Fresnel reflection coefficients and reflection ellipsometry

We compare two free-space reflection methods dedicated to the determination of the complex permittivity of materials at microwave frequencies. Original numerical methods, based on constant value lines charts and nonlinear least squares optimization, have been developed for each approach. Results are given in the case of homogeneous, single layer building slabs of finite and infinite thicknesses.