The tag, as already pointed out, is activated by means of an electromagnetic field generated by the scanner (reader), which is the electronic device used for the exchange of information with the tag itself. The readers can be portable (see Figure 5.15b), and are used by operators or are installed on vehicles, integrated with an antenna. The fixed RFID readers (see Figure 5.15c) are integrated with groups of antennae such as gates, portals or tunnels.