In this paper, a modified SIW cavity is applied to mitigate the blind spot and improve the radiation pattern of the patch antenna element in phased array. The active element pattern is changed as desired because of modified SIW cavity, leading to increase of 3-dB scanning range of the phased array. A probe fed patch antenna element and its phased array of $8\times 8$ unit cells with cell spacing of $0.53 \lambda_{0}$ on a double-layer substrate was designed. Full-wave simulation is applied to validate the design. Compared with conventional SIW cavity backed patch phased array, the gain of the proposed phased array antenna at 16.7 GHz is approximately 2.2 dB higher when the main beam is steered at +45 degree from boresight in E-plane. In addition, the element size and profile keep unchanged.