An embodiment antenna having first dimension and second planar arrays. The first array has a first element spacing in an x- and a y-dimension and is operable in a first frequency band. The second array has a second element spacing in the x-dimension and the y-dimension, and is operable in a second frequency band. The second planar array is displaced from the first planar array in a z-dimension for co-aperture operation of the arrays, and is disposed parallel to and in a near-field of the first planar array. Elements of the second planar array are disposed and steerable, in a u-v plane for interleaving a first plurality of grating lobes generated by the first planar array with a second plurality of grating lobes generated by the second planar array.