A transmitting radio node (10) precodes a transmission from an antenna array, which includes antenna elements arranged along at least two axes, using a main codebook which is representable as a Kronecker product of a first codebook and a second codebook, where the first codebook comprises predetermined sub-precoders and the second codebook comprises configurable sub-precoders. A receiving radio node (20) may benefit from adaptive beamforming made possible by the configurability of the main codebook, while still using a stable format, which remains valid also after reconfiguration, for the exchange of reference signals and corresponding feedback information.