Abstract: Flat end-fire antenna is not consistent with the antenna arrays. In order to get high directivity,the space of the array should be increased and best result can be got on 1.5 wavelengths, but since gating lobe is produced concurrently, sparse array is adopted.Extending the sparse constraints of regular grid from 0.5 wavelengths to 1.5 wavelengths,by simulation,this kind of array is found to be inconsistent with the theory of antenna arrays with constraint of 0.5 wavelengths, high sidelobe level is produced at the same time.Array antenna powered by uncorrelated signal is proposed,with which the problem of pattern synthesis with constraints of the minimum element spacing is 1.5 wavelengths with lower maximum relative sidelobe level is solved effectively.The computer simulation results confirm the validity of this method.