Effects of Al2O3 doping on the dielectric properties of barium strontium titanate for application in phased array antennas have been studied. The grain size of the specimen is maximum for barium strontium titanate doped with 1 wt% Al2O3. The density and the real part of the relative dielectric constant decreases with increasing Al2O3 content. The loss factor is minimum for barium strontium titanate doped with 2 wt% Al2O3 content. The real part of the dielectric constant and the loss factor with frequency of all the specimens is stable in the measurement frequency range from 1 MHz to 40 MHz. The real part of the dielectric constant of the specimens decreases with increasing applied DC field. The loss factor of the specimens is influenced much less by the DC field than the real part of the dielectric constant. The tunability is about 24% for barium strontium titanate doped with 1 wt% Al2O3 content.