A testing system optimizes a cost function of a theoretical spatial cross correlation and a spatial correlation obtained with antenna elements (402 to 416) for determining weights of the antenna elements (402 to 416), and forms a beam of a signal of at least one path of a simulated radio channel with at least two antenna elements (402 to 416) of a plurality of antenna elements (402 to 416) coupled to an emulator (418) in an anechoic chamber. The at least two antenna elements are capable of polarizing the beam in a known manner.