Getty Images
Active vs. passive RFID tags: Which to choose
There are benefits and challenges to both active and passive RFID tags. An organization should learn what they are and what they do before implementation.
RFID tags could be a worthwhile investment, but supply chain managers may have uncertainties about where an RFID-based system fits into a workflow. An RFID implementation can eliminate inefficient procedures. Distinguishing between the two main types helps determine if an RFID system is worth undertaking.
RFID technology enables enterprises to track inventory, assets and equipment. Two broad categories denote RFID systems: active and passive RFID tags. The main difference between active and passive RFID tags is that an active tag has a battery while a passive tag does not.
Many commercially used tags are passive, owing to their significantly lower cost, long life and small size. However, active RFID tags are a better fit for longer ranges, data capture and higher performance.
Supply chain managers should use this information to gain a broad understanding of RFID technology, the potential financial cost and the differences between passive and active tags for specific use cases.
What is an active RFID tag?
An active RFID tag is a small device that broadcasts a unique radio identifier code. They come in both transponder and beacon variants. A transponder version listens for a request from an RFID reader and transmits only when prompted. A beacon variant continuously sends a signal. As a result, the transponder version has a long battery life. In addition, it reduces unwanted RF noise in the vicinity of other devices. Low-energy Bluetooth beacons are one common implementation in the 2.4 GHz band that takes advantage of the low cost of Bluetooth equipment compared to other infrastructure.
Both transponder and beacon active RFID tags often communicate in the 433 MHz and 2.45 GHz radio ranges. Due to its transmission properties, versions that use the 433 MHz range function better around metal and water. Active RFID tags can support a read range of more than 100 meters.
What is a passive RFID tag?
A passive RFID tag is more straightforward than an active tag. It consists of an antenna connected to an integrated circuit. An RFID reader transmits a unique radio signal to the passive tag, and the signal gives power to the RFID tag. The lack of power sources significantly reduces the cost and complexity of passive RFID tags compared to active RFID tags.
Passive RFID tags can be incorporated into stickers, cards and other small form factors and mass-produced at low cost. As a result, they are the most common choice for supply chain applications such as inventory management and asset tracking. They also support more radio ranges, including a 125-134 KHz range for a few inches, a 13.56 MHz range for a few feet and an 865-960 MHz range for tens of feet.
The costs associated with RFID tags
Active RFID systems tend to be more expensive than passive ones, though Bluetooth-based tags cost as little as one US dollar at the low end. However, Bluetooth Low Energy is more susceptible to performance and interference issues. Premium variants can cost more than a hundred dollars.
Meanwhile, small printed passive tag stickers cost a few cents, while environmentally hardened or secure variants run a few U.S. dollars. However, smaller tags have less of a range, and in general, active RFID makes a better choice for more extended read-range applications.
The differences between active and passive RFID tags
Each form has specific use cases where they work best. Active is better for tracking expensive objects. Passive's low cost enables mass deployment. Here are some scenarios where a company may prefer one approach over another.
- An active RFID tag captures supply chain data like humidity from perishable cargo.
- An active RFID setup can track the movement of valuable assets around a facility, such as medical equipment, repair carts or specialized tools.
- Active RFID is ideal for tracking assets over a wide area, such as automatically following the movement of a single company's containers at a busy shipping yard.
- Passive RFID is the best choice when changing batteries is impractical. For example, passive RFID is a good choice for livestock management.
- Passive RFID works well for tagging individual products for inventory control.
