Microwave measurements of dielectric constants of ceramic materials by powder mixture equations

Microwave dielectric constants of composite samples made by high dielectric constant ceramic filler dispersed in the polyethylene matrix are studied in this article. The filler material of strontium titanate ceramic has a dielectric constant of 300 at microwave frequencies. The logarithmic and exponential mixture equations and a newly published mixture equation were adopted in this study. The matching condition of the theoretical curves of various mixing rules with experimental dielectric constant values of the mixtures is investigated. The dielectric constant of pure ceramic is then calculated from the measured dielectric constants of composites under various filler concentrations by these mixing rules. The theoretical errors of estimation of various rules are derived and analyzed. The best mixture equations for measuring the dielectric constants of ceramic materials will be recommended.