RFID or Radio Frequency Identification is a form of technology that requires many parts to work together in order to achieve the desired result, which is to send information or signals from a tag to a reader in order to be used or understood. These signals or radio frequencies are emitted from tags and then thanks to an RFID antenna, which transmits the information, these tags can be read or identified by a reader.
How does an RFID antenna work?
In an RFID system, the antenna converts electrical current into electromagnetic waves and also listens for and receives electromagnetic waves from RFID tags. These tags contain data or information which needs to be read by an RFID reader and the only way the information can be transmitted or moved from the tag to the reader is via an antenna. The tags also “harvest” the energy needed to transmit electromagnetic waves of its own from the antenna’s waves.
Tags or identifiers can be placed on many different sorts of products or objects that need to be tracked. From moving objects like vehicles or conveyor belts to stationary objects like stock items or furniture, RFID tags are used for a multitude of purposes.
The antenna is an integral part of the RFID system (as is the tag and the reader) and without any of these parts working efficiently together, the system itself would not run either.
Types of RFID antenna
There are two different types of RFID antennas, namely; linear polarized antennas, circular (left-hand and right-hand) polarized antennas. The antenna type mostly depends on how the antenna sends electromagnetic waves. How far and wide the antenna spreads these waves depends on the design and how much power it can use. We will also discuss monostatic or bistatic antenna configurations. Let’s discuss each of these now in detail:
Linear polarized antennas
Otherwise known as dipole antennas these antennas read and transmit their electromagnetic waves in one plane or direction; either vertically or horizontally. This antenna type is used most often when the tag is fixed i.e placed on an object permanently and the antenna is able to read the information from the same source in the same position every time.
Circular polarized antennas
These antenna types are also known as helix, patch and crossed dipole antennas. Unlike the linear polarized antennas, these antennae are able to receive and emit information through electromagnetic waves in two planes therefore creating a circular effect. Think of a corkscrew; the waves revolve in a circular motion continually emitting information in a rotational manner. This type of antenna is most often used when the tag location is not fixed or known and so the antenna (through its circular rotation) will be able to pick up information at any point from the tag when it comes into its path.
Monostatic circular or bistatic circular antenna configurations
The difference between these two configurations is that in a monostatic system the antenna sends and receives signals or waves from a single common port. In a Bistatic set-up, two RFID antennae are used and one antenna only sends signals and the other only receives signals. Monostatic configurations are the most commonly used because it has lower cost and space requirements.
Antennas in general come in a variety of shapes, forms, uses and degrees of toughness. Antennas are vital to the RFID system because without them, the information contained within the tag cannot be read.
Integrated Readers and Antennas
In some systems there is a need for an antenna and reader to be integrated and these kinds of configurations are certainly available. However, integrating an antenna and reader could limit the systems scalability at later stages, especially if more than antennas are needed.