Flexible ceramic-polymer composite substrates with spatially variable dielectrics for miniaturized RF applications

Official URL: http://192.168.1.20/record=b1293640 (Table of Contents)

Multi-functional miniature RF devices play an important role in meeting challenging future demands within the modern communication industry. This in turn creates the need to design microwave dielectric materials with superior electrical and mechanical properties such as dielectric tunability, miniaturization, flexibility, and low loss. Although many ceramic-polymer composite substrates are presently available for RF applications, no simple manufacturing process exists today capable of producing composite substrates satisfying both high dielectric constant and low loss for miniaturization and the desired mechanical property such as flexibility for conformal applications. In order to compromise between high dielectric constant and flexibility, ceramics (MCT powders) and organic binders (polymer solution) are mixed and fabricated as films through a process called tape casting in this thesis. Prior to optimizing the process, several studies are carried out: MCT spray dried powders with k=70 and k=20 were analyzed as pressed and produced into a tape cast film. Dielectric behaviors of the samples are measured by the Agilent 16451B impedance analyzer, their microscopic behavior is examined by scanning electron microscopy. Results demonstrate that a dielectric constant 21 and 9, respectively can be achieved for nonsintered films that are deformable. Fabrication of spatially variable conformal substrates is investigated next where mosaic structures are fabricated using tape cast films and three different methods. In order to demonstrate the performance of the resulting substrates, these substrates are used to construct patch antennas and their return loss performance is measured with an Agilent Network Analyzer. For possible future design studies, antennas are also simulated using COMSOL Multiphysics 3.5a software.