A dual-Band phased array antenna with built-in grating lobe mitigation includes an array of radiating elements capable of working at both bands and arranged at distances small enough, avoiding grating lobes with respect to the lower band within the desired field of view. The radiating elements are arranged in planar subarrays that can be steered independently from each other and each of the subarrays has a different boresight normal vector, so that grating lobes in the upper band is mitigated.