A 4–8 GHz ultra wide band microstrip array antennas with improved gain for weather Radar applications was designed and fabricated. The microstrip radiating elements of the proposed array antennas are powered using a T-junction power divider with quarter wave-transformer impedance for a best matching. The design of this array antennas is based on the geometry of a linear array antennas well studied [ref (8)], which is based on minimizing of the electromagnetic (EM) coupling between the radiating elements and as decreasing the number of side lobes. The array antennas with dimension of (110 × 214 × 1.58 mm3) is fabricated on FR-4 epoxy dielectric with relative permittivity of 4.4 and thickness h = 1.58 mm, it is performed in the full-wave EM solver High Frequency Structure Simulator, CST and verified by measurement. The proposed broadband array antennas show a better performance than the references antennas in deferent parameter which cited after.