In this article, we study the angular plane waves expansion of the standing electric field within a reverberation chamber. For this purpose, we adapted a high resolution Root-MUSIC based method to the context of the reverberation chamber by using a decorrelation procedure to estimate the angles of arrival and complex amplitudes of the planes waves. Using FDTD simulations to get the standing electric field cartographies, we demonstrate, at low frequencies, that directions of arrival are slightly affected by the stirrer rotation whereas the wave amplitudes are strongly perturbed. This result indicates that stirrer works as a plane wave powers tuner.