Curve fitting of DC field dependence of dielectric constant of barium strontium titanate powder prepared by sol-gel process

Effects of a DC-biasing field on the real part of the relative dielectric constant of barium strontium titanate powder prepared by the sol-gel process for application in phased array antennas have been studied. The real part of the relative dielectric constant of specimens decreases with increasing applied DC biasing field. An overall tunability of 15.7% at 1.5 kV/cm is achieved. The real part of the relative dielectric constant of specimens decreases rapidly before 1.0 kV/cm and slowly after 1.0 kV/cm when compared with the fitting data obtained by curve fitting with Johnson's bias equation. With the introduction of a bias exponent coefficient in the denominator of Johnson's bias equation, a modified bias equation is proposed. The data obtained by fitting with this proposed modified bias equation provide a more accurate description of the DC biasing field dependence behavior than those obtained by fitting with Johnson's bias equation.