This paper presents a fast iterative method for the synthesis of linear and planar antenna arrays of arbitrary geometry that provides
pattern reconfigurability for 5G applications. The method enables to generate wide null regions shaped according to a Gaussian
distribution, which complies with recent measurements on millimeter-wave (mmWave) angular dispersion. A phase-only
control approach is adopted by moving from the pattern provided by a uniformly excited array and iteratively modifying the
sole phases of the excitations. This allows the simplification of the array feeding network, hence reducing the cost of realization
of 5G base stations and mobile terminals. The proposed algorithm, which is based on the method of successive projections,
relies on closed-form expressions for both the projectors and the null positions, thus allowing a fast computation of the
excitation phases at each iteration. The effectiveness of the proposed solution is checked through numerical examples compliant
with 5G mmWave scenarios and involving linear and concentric ring arrays.