Cell sectorization is used extensively to increase the capacity of cellular systems; however, inter-sector interference caused by non-ideal sector antennas hinders full realization of sectorization benefits. We propose a new technique for sector beam synthesis, using phased antenna arrays, to minimize inter-sector interference, or equivalently, to maximize the beam efficiency. A peak-to-peak ripple constraint on the power density inside the sector leads to a non-convex optimization task; a reparametrization results in an easily solved convex fractional linear program. The proposed procedure accommodates non-isotropic antenna elements, arbitrary element spacing, and arbitrary sector boundaries, but is limited to uniformly spaced linear (or planar) arrays. Finally, the proposed method is used to predict antenna array size requirements for a DS-CDMA cellular system.