Active RFID systems use self-powered RFID tags that continuously broadcast their own signal. Active RFID tags are commonly used as “beacons” to accurately track the real-time location of assets or in high speed environments such as tolling. Active tags provide a much longer read range than passive tags, but they are also much more expensive.
Passive RFID systems use tags that are powered by the electromagnetic energy transmitted from an RFID reader. Passive RFID tags have applications including access control, file tracking, race timing, supply chain management, smart labels, and more. The lower price point per tag make employing passive RFID systems economical for many industries.
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 – 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.
Tasked with weathering harsh environmental conditions such as extreme temperatures and moisture, some active RFID tags may be encased in a rugged shell. Because of the size of the enclosed battery, circuitry, and bulk of a durable exterior, active RFID tags are usually much larger than passive tags. Also, some active tags may have on-board sensors that track environmental parameters.
All these additional features translate to increased costs for the customer, but the return on investment of a system may far outweigh the initial costs. The prices of active RFID tags range anywhere from $20+ to $100+ depending on the tag’s ability to withstand harsh conditions and other key functional features of the tag. Given the required investment of an active RFID system, active tags are usually reserved for tracking high worth assets or for items where accurate location tracking is necessary to the success of the system.
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.
Since passive RFID tags do not have their own power source, they typically have lower memory capacities and significantly shorter read ranges than their active counterparts; however, passive tags are drastically cheaper with prices ranging from pennies up to several dollars. Passive RFID tags are much smaller than active tags, and depending upon the application, passive tags may be as thin as a few sheets of paper.
As the cost of passive RFID tags continues to decrease, a greater number of industries are adopting the technology, and many companies are replacing standard barcodes with RFID labels. Passive tags are found in asset tracking, tool tracking, event monitoring, access control, race timing, and variety of other applications.
While both active and passive RFID technologies use radio frequencies to communicate information, each is very different, and likewise, possess different qualities well suited for varying applications.
If you have any questions about active and passive RFID, leave a comment below of email us at info@atlasRFIDstore.com.