Active Vs. Passive RFID For Location Tracking [2021 UPDATE]

In a world of evolving technologies, businesses have many great tools to help them accomplish their goals. However, determining which technologies that can both provide for the needs of the business while being cost-effective can be hard. One of those technologies is radio-frequency identification, or RFID.  

RFID tags are embedded into most common day applications, such as retail security tags, employee badges, inventory control, pay terminals, and even animal identification. There are two fundamental types of RFID tags available, so which one do you choose?

Passive RFID Tags

The first type of RFID available is passive RFID. Passive RFID uses high-power readers that send out a low-frequency, high-power RF signal to battery-free tags. The antenna in the tag is woken up by the amount of energy flowing to it, which wakes up its circuit. 

The tag then transmits a coded message back to the reader at a different frequency. Passive RFID technology is often used for inventory tracking and to deter theft.

Active RFID Tags

Another option is active RFID. Active RFID uses battery-powered tags that advertise their identity to various access points or readers. These access points often then transfer the location of each tagged item to a gateway. 

Active RFID technology can be used for various forms of asset location management and real-time location systems (RTLS systems).  For example, AirFinder active RFID tags calculate their location relative to reference points and send this data to nearby readers. 

The readers then send the location data to the gateway, which is then sent to the AirFinder web application. The application takes the data and provides the user with an estimated location of each tagged asset.

Active Vs. Passive RFID: A Comparison

Use Case Examples

Active: Monitor physical location of a tagged object

Passive: Keep track of inventory located in a specific room

Range and Scalability

Active: Active RFID range can be greater than 100 feet between the RFID tag and reader.  This allows Active RFID systems to scale easily since you could potentially 10,000 square feet with one Active RFID reader and a few reference points.

Passive: Passive RFID range is roughly 1-5 meters away from the Passive RFID reader, so scalability for tracking the location of an item would require a large number of readers.

Tag Costs

Active: Active RFID tags cost between $5 and $15 each.

Passive: Passive RFID tags cost anywhere from $0.10 to $0.50 each.

Tag Battery Life

Active: Active RFID tags usually last between three to five years, depending on the battery.  Some tags may allow for battery replacement, while other tags may not. These tags also last much longer than other RTLS technologies such as ultra wide-band tags and WiFi tags).

Passive: Passive RFID tags are simple and battery-free—meaning they’ll last virtually forever, which is a big part of their appeal.

Environmental Constraints

Active: Active RFID tags may be more difficult to use in rugged environments, and may not always withstand the autoclaving process - so if sterilization is required, be sure to consider all your options.

Passive: Passive RFID tags are easier to completely seal, which may make them better for rugged environments.

Can active and passive RFID tags work in tandem?

Yes! In fact, that’s something AirFinder is examining for the future. We’re currently looking into adding passive functionality into our active tags, for two reasons. 

First, it can provide time-sensitive chokepoint functionality, so we’ll be able to tell more accurately if a tagged item leaves a particular area. Second, it gives those who require active RFID scalability but could use passive RFID functionality a better option in the market. Stay tuned for updates!