This paper presents two different approaches for the efficient computation of beam coupling factors (BCF) in antenna arrays. First, an analytical expression is derived for the case of symmetric radiation patterns with sin (θ) variation. Then, an efficient approach is presented for the numerical computation of such quantities in larger arrays. This approach is based on the combination of the Macro Basis Function (MBF) technique with the Method-of-Moments (MoM). Both impedance and scattering matrices formulations are considered to provide the BCF matrix.