Fabrication, Measurement, and Application of Compressible Artificial Materials

Fabrication and measurement of compressible composite artificial materials is presented. The composites are mixtures of an elastomer and a ceramic powder with effective relative permittivities ranging from 2.8 to 12.5. The fabrication procedure and its related challenges are detailed along with the benefits inherent to these materials. Accurate characterization of these composites is difficult, since compression during measurement can lead to errors in their extracted permittivities. A proposed solution to this problem uses a density normalization method to remove compression errors from the measured permittivities. Knowledge of the permittivity resulting from specific mixing ratios of the elastomer/ceramic materials benefits designers when creating devices requiring specific dielectric constants. Two microstrip applications are introduced that illustrate the benefits of heterogeneous substrates. One is an edge-loaded patch antenna, and the other is a miniaturized 90
^°
hybrid coupler. The metal area of the patch antenna was miniaturized by nearly 30% with some reduction in gain and an increase in bandwidth. The coupler exhibited a reduction in area of more than 75% over a conventional design with minimum loss in bandwidth.