We provide an efficient Method-of-Moments analysis of 2D fields radiated in a typical indoor environment which is applied to the wireless power transfer from a multiple-antenna access point to multiple devices. These simulations allow the computation of the correlation matrix obtained at the access point array when several devices are active. Power focusing capabilities from the same array are then analyzed, including multipath effects. This technique is based on the eigen-analysis of the correlation matrix measured at the access point and presents similarities with time reversal