Free space transmission measurement of complex permittivity of insulator materials is demonstrated in this thesis. Further aim was to determine how the complex permittivity is related to the moisture content, and the density of the measured materials. A successful implementation of the presented method could be used in various industrial applications related to moisture content and density measurement.
After the overview of methods of measuring the electromagnetic properties of materials, the applied free space method is presented with its simple physical background assuming plane-wave propagation. Microstrip and biquad antennas were designed for the measurement at 2.4 GHz and 3D numeric simulation was created in Ansoft HFSS for modeling the measurement configuration. As a result, measurement data of sand and wood material, analytic and numeric calculations are presented.
Using the presented configuration, the solution to the problem was partly successful, although the presented measurements and simulations can provide a better approach to create a similar, but successful measurement configuration.