RFID antennas or Radio Frequency Identification antennas are devices that are used in a specially designed wireless system that is made up of two major components, tags and readers. The reader is a device that is typically made up of one or more antennas, these antennas receive and emit radio waves to and from the RFID tag.
RFID antennas firstly transmit power to the RFID tags by activating them, then they will receive data back from said activated tags. The antenna itself has no intelligence on its own and has to be completely controlled by the RFID reader.
There are two main types of RFID Antenna, these are linear and circular polarized antennas, below talks about both of these types of antenna in more detail.