Experimental Investigations on the Frequency- and Temperature-Dependent Dielectric Material Properties of Soil

Frequency- and temperature-dependent complex permittivity or conductivity of a silty clay loam were examined in a broad saturation and porosity range with network analyzer technique (1 MHz-10 GHz, 5 °C-40 °C, coaxial transmission line and open ended coaxial cells). An advanced mixture model based on the well-known Lichtenecker-Rother model (ALRM) was developed and used to parameterize complex permittivity or conductivity at a measurement frequency of 1 GHz under consideration of a dependence of the so-called structure parameter as well as the apparent pore water conductivity on saturation and porosity. The ALRM is compared with frequently applied mixture models: complex refractive index model, Looyenga-Landau-Lifschitz model, Bruggeman-Hanai-Sen model, and Maxwell-Garnet model as well as empirical calibration functions. Comparison of ALRM applied to the investigated frequency and temperature range with sophisticated broadband relaxation models indicates the potential and the limitation to predict the high-frequency electromagnetic material properties.