Dielectric Measurement of Powdery Materials using a Coaxial Transmission\n Line

The following study investigates the use of a coaxial transmission line for\ndetermining the properties of powdery dielectric materials (1-10GHz). Four\npowdery materials with dielectric constants ranging from 3.5 to 70 (SiO$_2$,\nAl$_2$O$_3$, CeO$_2$, and TiO$_2$) were experimentally investigated at varying\nvolume loading fractions. Powder particles were mixed with a paraffin matrix\nand properties of the powder were analyzed using ten mixing equations to verify\ntheir accuracy. These powder-paraffin composites were also modeled at varying\nvolume loadings for comparison with experimental data to gain a better\nunderstanding of the interactions between the different phases. The optimal\nvolume loading fraction was determined to be 10% for all powders tested. A\nmetric for selecting the most well-suited mixing equation was proposed that\ninvolved taking the ratio of the particle dielectric to that of the matrix.\nThis study ultimately provides guidance for experimentally measuring the\ndielectric properties of unknown powdery materials that have application for\nnew devices that utilized powder-based dielectric materials.\n