A novel solution for conceiving wide band (multi-band) array antennas is presented. The solution is based on the concept of interleaving sparse, sub-arrays operating at separate frequencies. Sparse array antennas offer two major advantages, namely: they have non-uniformly distributed elements, with possibly large distances between elements (this providing the necessary space for interleaving different sub-arrays), and they do not require the amplitude tapering of the elements for controlling the array radiation pattern.