The present invention relates to a wireless communication system node, which comprises an antenna arrangement, with at least one array antenna, each array antenna having a plurality of antenna elements. At least a first set of antenna elements is formed from said plurality of antenna elements. For at least one set of antenna elements, a control unit is arranged to: Form an antenna beam that is steerable to a certain pointing angle in at least one plane for a signal having a certain bandwidth with a certain lowest frequency (flow) and a certain highest frequency (fhigh) Determine the relative power of a received signal at a plurality of frequencies in the frequency band. Determine a degree of angular pointing deviation (βb, βc) for the antenna beam relative the received signal by means of the degree of slant of the relative power of the received signal.