Design and characterization of a measurement system for dielectric spectroscopy investigations on granular materials in the 2.45 GHz ISM band

The design and preliminary metrological characterization of a waveguide system for complex permittivity measurement on both compact and granular materials is presented. The proposed system is intended for the dielectric characterization of asphalt concrete and of its components at frequencies around 2.45 GHz. Therefore, the system easily allows performing measurements on granular materials, such as mineral aggregates found in the asphalt concrete. A series of experimental tests on reference materials shows, via comparison with a standard measurement system, errors within 1%. A theoretical analysis of uncertainty contributions confirms a predicted expanded uncertainty lower than 5%.