Microwave properties of composite ceramic phase shifter materials

The microwave properties of bulk ceramic barium strontium titanate and non-ferroelectric oxide composites are measured at X-band with a cylindrical mode-filtered resonant cavity. A helical wire-wound waveguide makes up the cavity's cylindrical wall, which permits the use of high-purity TE01p resonant modes for high accuracy permittivity measurements. Measurement results at 300K show that microwave dielectric losses increase as the stoichiometric percentage of barium increases. The real. relative permittivity increases with decreasing weight percent of added non-ferroelectric low-loss oxide. Dielectric losses rapidly decrease with the addition of a relatively small amount of non-ferroelectric oxide.