Active Vs. Passive RFID

A question we are often asked when speaking with potential clients is, “what is the difference in price between active and passive RFID tracking systems?” Seeing as this is such a popular question, we wanted to address it here on our blog. The short answer to this question is that there is no short answer. There are too many considerations required to determine what will be the most cost-effective solution for a specific project to give a blanket answer to what the price differences are.

What I can say is that passive RFID tags generally have a lower cost per tag than semi-passive and active RFID tags do; however, to say that passive RFID tracking systems are significantly more affordable than active systems would be inaccurate. Tag costs are only one aspect of the hardware needed for an RFID-based tracking system. Infrastructure costs for readers and antennas are also important details that RFID experts consider when providing quotes. Utilizing passive tags may be the most cost-effective solution in one application while active tags may be the most cost-effective solution in another. So, when doing research on what to budget for a tracking system, it is best to take the time to speak with experts about your tracking needs and get thoughtful, accurate quotes for your specific system needs.  

To arm yourself with information for those conversations, keep reading for explanations on how active and passive RFID tags and systems work, typical applications that are best fit for different hardware options, and more.

Passive RFID

In passive RFID systems, the RFID tags don’t contain a battery so they must be powered through a process called backscatter.

Backscatter

Backscatter is a term that describes the process of an RFID reader antenna (or RFID hand scanner) signal momentarily powering an RFID tag with just enough energy for that RFID tag to respond back to the antenna with a signal of its own.

A visual representation of backscatter
Read ranges

There are hundreds of different types of passive RFID tags though and the read ranges for different tag types vary. One important consideration to note is that smaller tags often have weaker signals and need antennas (or hand scanners) to be closer to a tag for the backscatter process to work successfully. This is not necessarily a bad thing, just something to note.

Many applications using RFID systems work fine with small RFID tags that have a low read range. For example, library systems that use RFID for checking books in and out work well with tags that require a low range. Patrons can select the books they would like to check-out and bring them to a check-out station that scans the RFID tags, meaning the RFID tags do not need to emit signals that reach 20 feet.  The check out area needs to be limited to a range of 2 feet or less. So, short range passive tags work great in that scenario. On the other hand, in a retail setting where inventory needs to be conducted frequently and easily, passive RFID tags that have a longer range can be of big benefit for organizations that need to batch-scan all items in a particular area with just a wave of a hand scanner.

There are hundreds of RFID tags to choose from and there absolutely is an option that will fit your needs. For help choosing the best hardware for your organization, speak to an Enasys RFID expert today.

Active RFID

One of the key differences between passive RFID tags and active RFID tags is that active tags contain internal batteries, meaning they don’t need to be powered via backscatter and can emit signals on their own. In the past, active RFID tags would need to be replaced completely when the batteries depleted (after around 3-5 years of use), but now there are active RFID tags on the market that allow for batteries to be replaced. This is a wonderful development because active RFID tags have a higher associated cost per unit than passive tags, and not having to replace the tags completely when the batteries die makes active RFID tags more accessible.

Beacons

Active RFID tags are called beacons because they are always emitting signals. 24 hours a day, signals are beamed out every few seconds until the internal battery is depleted and needs to be replaced.

The costs associated with beacons depend on the type of technology that they use to emit signals. Ultrawideband tags are typically between$30 and $50 a tag, while Low Energy Bluetooth tags are typically between $5 and$15, and Wi-Fi tags are between $60-$75 each.

Types of Active Asset Tracking Systems

Ultrawide Band

Unlike other active asset tracking systems that track general location of assets on pre-mapped zones, ultrawide band systems track an asset’s location in three-dimensional space with accuracy under one foot of space. This type of granular tracking uses what we refer to as “XYZ location data”, which refers to x, y, z coordinates in a three-dimensional map.

Tracking an assets’ location this way allows for pin-pointing exactly where an asset is—all the way down to what shelf level the asset is on. A great example of when this type of tracking is particularly useful is in pallet tracking in warehouses when it can be hard to see what pallets are on high shelves, especially when shelves hold multiple pallets in depth.

Bluetooth Low Energy (BLE)

If your needs would be filled with just x and y location data and accuracy within five feet, then Bluetooth Low Energy may be a good fit. A benefit of BLE is that it is incrementally scalable, meaning that a system can be started in one zone and expanded into other zones slowly. The tags are also rather affordable compared to the other active systems.

Wi-Fi Tags

Wi-Fi tags are the most expensive option in the group and provide the lowest granularity for location accuracy at 25 feet; however, as we have discussed, application of an asset tracking system is of vital importance when choosing the best hardware for your team’s needs. Wi-Fi systems would be well suited for a small business that wants to use the Wi-Fi hardware they already own to implement a tracking system that gives zone-level location information on where valuable items end up, rather than invest in many readers and antennas for a more granular location tracking like UWB or BLE. Although the cost per tag is high, there is less additional hardware needed for the rest of the tracking system, which makes Wi-Fi systems more affordable than other options. Wi-Fi systems would likely not be the ideal choice for tracking the location of portable ultrasounds in a busy hospital, for example, because the location accuracy is not granular enough and a large scale real-time location system would be difficult and complicated to support via Wi-Fi.

Selecting the right asset tracking system for your organization

All in all, there is far more detail that can be provided about each of the hardware options and asset tracking systems on the market. At Enasys, our goal is to arm you with enough knowledge for you to make informed decisions, but not too much knowledge to make your head spin. Give us a call (1-800-633-2902) or reach out here and let us help you determine what asset tracking systems will best fill your needs for the lowest cost. We are more than happy to help!

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