Ferroelectric phase shifters for phased array radar applications

The use of ferroelectric materials in the design of phase shifters for RF applications is proposed as a means of overcoming the limitations of current technology. A simple and novel design is outlined, and test results are presented. The ferroelectric phase shifter design is based on a material whose dielectric permittivity can be made to vary by application of a DC electric field, parallel to the polarization of the RF energy, and normal to its direction of propagation. One barrier to the application of ferroelectrics to device designs has been the unavailability of a low-loss voltage-tunable material. Recently, a member of the perovskite family, a ceramic consisting of a combination of barium and strontium titanate (BST) was reported to exhibit a permittivity of 3000-4000 with a loss tangent less than 0.01 in the centimeter wavelength region