RFID stands for radio frequency identification. It is an automatic identification technology whereby digital data is encoded in an RFID tag or "smart label" and is captured by a reader using radio waves. Put simply, RFID is similar to barcode technology but uses radio waves to capture data from tags, rather than optically scanning the barcodes on a label. RFID does not require the tag or label to be seen to read its stored data—that's one of the key characteristics of an RFID system.
Tags can be read using handheld or mobile readers, shelf or tabletop readers, or readers that can be installed at doorways or in portal configurations. A line of sight is not required – tags can be read automatically, even through packaging materials and in transit, whenever moving items or people come within range of a reader.
RFID systems greatly streamline inventory and asset tracking, virtually eliminating human error while providing instant, detailed records of the movement of assets.
How Does RFID Work?
RFID works by employing an RFID transponder (or tag) and a reader. The RFID transponder is comprised of a microchip that holds information to identify an object, product, or person and an antenna for transmitting this data to the reader.
The antenna transmits the data to a reader that converts the radio waves to usable information. Unlike bar code and magnetic stripe technology, RFID transponders can be read anywhere within the magnetic field sent out by the reader. Radio waves can travel and be read through many non-metallic objects. Depending on the power of the reader, an RFID antenna can be read from direct contact up to 20 feet.
In passive systems, which are the most common, an RFID reader transmits an energy field that "wakes up" the tag and provides the power for the tag to respond to the reader.
Passive tags do not have a battery and draw their power from the reader. The reader sends out electromagnetic waves that induce a current in the tags antenna. Since these tags obtain their power from the reader, they generally have shorter read ranges and are in a defined reader zone. Passive RFID is relatively inexpensive and found in many daily surroundings. They can be very small with size dependent on the type of tag antenna.
In active systems, a battery in the tag is used to boost the effective operating range of the tag and to support additional features over passive tags, such as temperature sensing. Data collected from tags is then passed through communication interfaces (cable or wireless) to host computer systems in the same manner that data scanned from barcode labels is captured and passed to computer systems for interpretation, storage, and action.
Active RFID tags work independently, so the tags themselves can transmit and receive data. As they generally transmit data over a longer distance they are physically larger and more expensive than passive tags and are operational as long as the battery is functional. Passive RFID is an optimum combination of benefit and costs and uses a frequency that fits most customer applications.
What Is the Frequency Range of RFID?
There are several radio frequencies in use.
- Low Frequency (LF): 125kHz
- High Frequency (HF): 13.56 MHz
- Very High Frequency (VHF): 433 MHz
- Ultra High Frequency (UHF): 860 - 960 MHz
- Microwave Frequency: 2.4 GHz
Tags and readers must use the same frequency in order to work together. Readers work on a specific frequency and the frequency depends on several factors such as read range, speed of data transfer, type of material and environment. Government and industry regulations also affect which frequencies are used.
Where Is RFID Used?
RFID is used where there is a high volume of items moving quickly in and out of an area and where there is a high selectivity and multitude of sizes, colors and styles.
Additional use cases include when items have a high value so anything that is important not to lose and when there is a need for traceability, such examples include food/cold chain and pharmaceuticals.
RFID was first used in retail but now its uses are expanding beyond retail to the supply chain. Technological advancements are driving new uses in manufacturing, transportation, logistics and healthcare.