Thick film fabrication of ferroelectric phase shifter materials

Abstract

Various composites of BSTO combined with other nonelectrically active oxide ceramics have been formulated. In general, the composites have adjustable electronic properties which can be tailored for use in phased array antennas and other phase shifting devices. The dielectric constant and the loss tangents have been reduced to enhance the overall impedance matching and thereby lowering the insertion loss of the device. In addition, the overall tunability, the change in the dielectric constant with applied voltage, is maintained at a sufficiently high level. The thickness limitation of the bulk materials is around 3–4 mils which can be used up to approximately 15 GHz. In order to increase the operating frequencies of the phase shifters, thick films were fabricated using non-aqueous tape-casting. The tapes were electrically characterized and compared to bulk ceramics. Also, laminated stacks of high dielectric constant and low dielectric constant alternating layers were fabricated.