RFID Terminology


Active Tag: A battery-powered RFID tag that powers the circuitry that transmits the signal to a reader. Active tags differ from passive tags in that they have longer read ranges, a higher price tag, and a larger size (due to the battery).


Antenna: The element built into both RFID readers and tags that radiates and receives radio energy.


Automatic Identification (also called automatic data capture): The ability to collect and enter data directly into computer systems without human involvement through technologies such as barcodes, biometrics, RFID, and voice recognition.


Backscatter: A method of communication where tags reflect back a portion of the radio waves that are emitted by the reader to transmit tag data to the reader.


Battery-assisted Tag: These RFID tags contain batteries that provide direct power to the tag  to increase read range (see semi-passive RFID tags.)


Circular-polarized Antenna: This omnidirectional UHF reader antenna emits radio waves in a circular pattern and is designed to capture RFID tags that are presented in different orientations easily.


Contactless Smart Card: Typically, a credit or loyalty card that contains an RFID chip that can automatically transmit information to a reader at extremely close ranges.


Chipless RFID Tag: An RFID tag without an integrated microchip (IC). Chipless tags work by incorporating materials in the tag that reflect back a portion of the radio waves beamed at them from the reader. The lack of an IC makes chipless tags inexpensive, but they cannot transmit a unique serial number. 


Closed-loop Systems: RFID tracking systems set up within a company, with no outside integration or required third party services.


Die: The silicon block onto which circuits are etched.


Electromagnetic Interference (EMI): Interference caused when the radio waves of one device distort the waves of another. Wireless computers, cell phones, and other RFID systems can produce radio waves that interfere with RFID tags. 


Electronic article surveillance (EAS): Simple electronic tags that can be toggled on or off. These tags are often used on expensive items in retail stores to prevent theft. When an unpurchased item passes through a gate the tag triggers an alarm to go off.


Electronic Product Code (EPC): A 96-bit code created by the Auto-ID Center that contains a unique identification number for a specific item in the supply chain. This unique number includes digits that identify the manufacturer, product category, and the individual item. The EPC standard is backed by the United Code Council and EAN International.


EPCglobal: A membership-driven non-profit organization that manages standards and numbering schemes associated with EPC. 
European Article Numbering (EAN): The barcode standard administered by EAN International and used throughout Europe, Asia, and South America. 


Excite: The reader is said to “excite” a passive tag when the reader transmits RF energy to wake up the tag and enable it to communicate back. 


Frequency: The number of repetitions of a complete wave within one second. Frequency is measured in Hertz.


Fixed Reader: When an RFID reader is referred to as "fixed", that means that the reader is secured (or installed) in a set location that it doesn't move from. The opposite of a fixed reader is a handheld reader.


GTAG (Global Tag): A standardization initiative of the Uniform Code Council (UCC) and the European Article Numbering Association (EAN) for asset tracking and logistics based on radio frequency identification (RFID).


GTIN (Global Trade Item Number): A GTIN is a GS1 identification key that enables global identification of an item anywhere in the supply chain. From manufacturer to consumer—the GTIN allows for any partner in a given supply chain to accurately identify the product and obtain pricing information. 


Harvesting: A term used to describe how passive tags gather energy from an RFID reader antenna.


High-frequency (HF) Tags: HF tags typically operate at 13.56 MHz and transmit data faster (but consume more power) than low-frequency tags.


Integrated Circuit (IC): A microelectronic semiconductor device in most RFID tags comprising many interconnected transistors and other components. 


Interrogator: An RFID reader is sometimes referred to as an "interrogator."


Interrogation Zone: An interrogation zone is an area in which the RFID signal is strong enough for an RFID reader to "excite" a passive tag to read its stored information.


Memory: The data stored on a tag.


Microwave Tags: Radio frequency tags that operate at 5.8 GHz. Microwave tags have very high transfer speeds, long read ranges (up to 30 feet), use a considerable amount of power, and are expensive compared to other RFID tags. 


Middleware: Computer software that connects software components or applications. It is used most often to support complex, distributed applications based on XML, SOAP, and service-oriented architecture (SOA). 


Near-field Communication (NFC): NFC is a term used to describe shorter-range wireless communication. To learn more about NFC, see our article What is NFC?


Nominal Range: The distance at which a tag can be read reliably.


Orientation: Refers to the relative position of the tag to the reader.


Passive Tag: An RFID tag that is powered by the RFID reader, instead of having a dedicated source of power (e.g., a battery). 


Portal: RFID readers that are designed to read multiple tags as they pass through a fixed location (or gateway), is called a portal.


Power Level: The amount of RF energy radiated from a reader or an active tag. The higher the power output, the longer the read range, but most governments regulate power levels to avoid interference with other devices. 


Radio Frequency Identification (RFID): A method of identifying unique items using radio waves. Typically, a reader communicates with a tag, which holds digital information in a microchip.


RFID Reader (also called an interrogator): The reader communicates with the RFID tag via radio waves and passes the information in digital form to a computer system. 


Read Range: The distance from which a reader can communicate with a tag. 


Semi-passive Tag: Similar to active tags, but the battery is used to run the microchip’s circuitry and not to communicate with the reader. Some semi-passive tags sleep until they are woken up by a signal from the reader to conserve battery life. 


Smart Label: A label that contains an integrated RFID tag that can store information, such as a unique serial number.


Transponder: A radio transmitter-receiver that is activated when it receives a predetermined signal. RFID tags are sometimes called transponders. 


Uniform Code Council (UCC): The nonprofit organization that oversees the Uniform Product Code (the barcode standard used in North America).


Uniform Product Code (UPC): The barcode standard used in North America. 


Write Range: The distance at which a tag can be written to by an RFID reader/writer without any object between the tag and the reader/writer.