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