Date of Graduation
Statler College of Engineering and Mineral Resources
Mechanical and Aerospace Engineering
This study proposes a standard methodology for coaxial dielectric property measurements of powdery materials (1-10GHz) using a coaxial transmission line. Four powdery materials with dielectric constants ranging from 3.5 to 70 (SiO2, Al2O3, CeO2, and TiO2) were experimentally investigated at varying volume loading fractions in a paraffin mixture. A statistically significant number of paraffin heterogeneous-mixtures was synthesized for all dielectric powders. The dielectric properties of the constitutive materials were determined using appropriate mixture equations. The sensitivity of the equations dielectric prediction to volume loading is discussed with guidance on selecting the best mixing equation. It was determined that low volume loadings of less than 10% were ideal for a general case where little to nothing is known about the sample. If the general range of the dielectric constant is known different mixture equations were found to be optimal for specific ranges. Furthermore, there was not a single mixing equation that proved best over the entire range of dielectrics studied. To this end, a standard testing procedure for powdery materials is justified, with guidelines for selection of an appropriate mixture equation. The justification is based on the ratio of the dielectric constant of the powder to that of the paraffin. These findings provide a baseline procedure for determining dielectric properties of new powdery materials that have applications in the area of microwave catalysis.
Tempke, Robert, "Experimental Measurement of Dielectric Properties of Powdery Materials using a Coaxial Transmission Line" (2019). Graduate Theses, Dissertations, and Problem Reports. 3933.