An apparatus includes an antenna array having a plurality of antennas. The antenna array is configured to receive a multi-carrier signal from a multi-antenna transmitter over a radio channel. The multi-carrier signal has at least two subcarriers, and each subcarrier is mapped at the transmitter to a respective subcarrier-beamformer. The respective subcarrier-beamformers has non-identical null and beam cone directions. A processor is configured to identify a communication direction for a radio signal communication between the apparatus and the transmitter. The communication direction is identified based on one or more specular path components of the radio channel which are related to a null or to a maximum of a subcarrier-beamformer.