In this paper, a microstrip patch array antenna for a Doppler radar at 10.525GHz is desinged and fabricated. To be used for mobile radar system, the antenna is fabricated on a single layer laminate to resist a fire impact and is covered with the Teflon foam. To obtain the desired characteristics, the array antenna is designed 4$ imes$8 array using a corporate 3-dB amplitude taper. Also, using square patch elements, the antenna can be converted to a circular polarized antenna later. The designed and fabricated array antenna has the reflection coefficient$({S_11})$ -53.498dB, the horizontal beam width of $10^{circ}$, the vertical beam width of $18.8^{circ}$, the gain of 21dBi, the bandwidth of 220MHz for VSWR<1.5 and a side lobe level of less than -17.5dB.