Keyword: Active RFID, Passive RFID, Tags, RFID,
Summary: What¡¯s the difference between Active RFID and Passive RFID?
Active RFID tags possess their own power source and transmitter enabling the tag to broadcast its signal. Performance capabilities include longer read ranges and greater memory capacities when compared to passive RFID tags; however, in order to achieve a significant read range and larger memory, these performance capabilities generate a greater demand for power. Typically, active RFID tags are powered by a long life battery that will last a few years, but will eventually require replacing.
Essentially, two different types of active RFID tags are available on today¡¯s market ¨C Transponders and Beacons. An active RFID transponder only communicates when in the immediate presence of a reader¡¯s interrogating signal, thus conserving battery life when the tag is out of range of the reader. Active RFID transponders are commonly used in secure access control and in toll booth payment systems.
Active RFID tags purposed as beacons will periodically transmit their identifying information at user defined intervals and RFID reader antennas will read and determine the tag¡¯s location with the help of back-end software. This type of active RFID tag is frequently used in real-time location systems (RTLS) commonly found in outdoor shipping yards and throughout supply chains. Some active RFID tags have a read range capable of reaching 100 meters in ideal outdoor environments.
Unlike active tags, passive RFID tags have no internal power source. A passive RFID transponder consists only of a microchip and an antenna; the two together are commonly referred to as an RFID inlay. As the name implies, passive tags wait for an interrogating signal from an RFID reader. Once the tag is within range of the interrogation zone, the RFID tag¡¯s antenna draws energy from the electromagnetic waves.
Once the tag¡¯s microchip, or integrated circuit, becomes powered, it transmits a signal. The change in the electromagnetic wave is detected by the reader¡¯s antenna which interprets the information. For the process to work properly, the antennas in both the tag and reader must be at least within several meters of each other; however, the read range depends on the transmit frequency, equipment settings, and other environmental factors.
Passive RFID tags generally operate at three distinct frequencies:Low Frequency (LF) 125 -134 kHz
High Frequency (HF) 13.56 MHz
Ultra High Frequency (UHF) 856 MHz to 960 MHz
As frequency increases, the radio wave¡¯s ability to penetrate liquids and metals decreases, and, generally, read range increases as frequency increases. Technology has improved in recent years, and specialized UHF RFID tags can operate around water and on-metal surfaces with minimal interference. Some applications, such as NFC payment systems, have adopted short read ranges as a unique feature. Near field communication (NFC) is a specialized subset of HF RFID and considers short read range a benefit and is a hallmark capability of the NFC protocol.