A data communication arrangement for elevators is disclosed. In the arrangement a directional antenna is used for transmitting data from elevator car. Correspondingly, the counterpart antenna in the end of the elevator shaft is transmitting with a directional antenna. In the elevator a further omnidirectional antenna is used to communicate with the terminal devices belonging to passengers. The properties of antennas may be adjusted based on the speed and location of the elevator car. In addition to the properties of antennas also other transmission characteristics may be adjusted based on the same information.