The present disclosure relates to dynamic antenna array reconfiguration and signaling in millimeter wave bands. A user equipment (UE) may detect an antenna array change condition. The UE may transmit a request for beam training for an antenna array configuration in response to the detecting. The request for beam training may include a requested antenna array configuration for the UE and an indication of beam weights to use with the requested antenna array configuration. A base station may determine whether to grant or deny the requested antenna array configuration for the UE. The UE may receive, from the base station, an indication of an antenna array configuration for the UE. The base station may transmit the number of reference signals as a set of contiguous channel state information reference signals (CSI-RS). The UE may train the reconfigured active antenna array configuration based on the reference signals.