Microwave High Dielectric Constant Materials.

Several areas of microwave technology require low-loss, temperature stable, high dielectric constant materials. The present program has as its objective the development of materials with these characteristics. There is no basis to expect to find compounds with these properties, so the approach taken involves mixing dielectrics with properties on either side of those required. Rutile has been selected as the high dielectric constant component for binary mixtures it has a large negative dielectric temperature coefficient, a dielectric constant of 100, and a microwave dielectric loss tangent of 0.0002. Candidate materials have been selected for mixing with TiO2 to achieve temperature-compensated dielectrics with dielectric constants in the 25 to 35 and the 40 to 80 ranges. Several have been prepared and preliminary dielectric data have been obtained. The difficulties involved in making measurements on high-k materials as a function of temperature are discussed, and a versatile microwave dielectrometer has been designed and built for these measurements. Author