There are two types of RFID tags such as passive or active tags. Passive tags do not possess power supply. When electricity is brought in the antennas by the radio frequency scan, it offers enough power for the tag for sending a response.
While passing through the electromagnetic field, the RFID tag detects the activation signal of the reader. Data are encoded in the integrated circuit of the tag. These are decoded by the reader. In order to get more information on RFID, you may search for RFID Chip Timing Redwood City California on the Internet.