Active vs. Passive RFID: Which Is Right for Your Use Case?
Radio Frequency Identification (RFID) tags can be a lifesaver when managing your company’s assets, but if you’re not an expert, it can be confusing to pick the right type of RFID tag for your business. Many RFID tags are on the market and have completely different use cases. Active RFID tags use a power source to increase their signal range, while passive RFID tags rely on electromagnetic waves to send a signal back to the scanner. If you want to further explore the differences and the unique use cases for active and passive RFID, that’s exactly what we cover in this article.
What is active RFID?
Active RFID tags are radio frequency identification tags with a power source (typically a battery) with a long range — up to 150 meters (around 490 feet) or more, depending on the frequency, tag size, and antenna.
(If you’re unsure what RFID is, read our introductory guide to RFID tracking.) While active RFID tags use RFID technology, their range and active transmission make them quite different from what you might expect from RFID tags. When they hear “RFID,” most people think of passive use cases like inventory management, scanning packages, or tickets to automated gates. Here, the tags are either passively sitting around and then getting scanned or (in the form of a ticket) moved toward a scanner manually. Passive RFID tags need that close proximity to work. But it’s an entirely different story with active RFID tags — they don’t share the same limitations. The increased range and its active transmission give active RFID tags a wide range of unique use cases — like real-time location tracking of assets. (More on this later.) To help you better understand how active and passive RFID differ, let’s further break down their key differences.
What are the key differences between active RFID and passive RFID
Four key differences exist between active and passive RFID tags: signal range, cost and lifespan, tag size and suitable attachment methods, and real-time monitoring vs. scanner-based activation.
The first difference is obvious: since an active RFID tag has a battery-powered transmitter, the range is much longer.
Passive RFID tags work through a clever antenna structure that lets them send response signals powered by receiving the signals from a scanner. The electromagnetic waves moving through the receiving antenna generate enough power for the response — AKA backscatter. That’s how they function without any internal power source — they only use the scanner’s output. As you might expect, standard RFID tags have a very short range, from as little as 10 cm up to 1.5 meters (four inches to five feet). These are often used for normal RFID asset tags without real-time location tracking. But by increasing the size of the tag (and therefore the antenna) and changing the wavelength frequency and power of the scanner, you can increase the range to around 10 meters (33 feet). These types of tags typically use very high-frequency ranges. So, they’re often known as UHF RFID tags — ultra-high radio frequency identification tags. Active RFID tags don’t rely on the power of the radio waves alone, instead using a battery-powered antenna. A beacon-type active RFID tag sends simple information (like the live location of the tag) at preset intervals. A transponder-type active tag acts more like a passive one — it waits to be activated by a scanner. The difference is the range — up to 150 meters (490 feet).
Cost and lifespan
Because of the battery, more powerful computing chips, and larger antennas, active RFID tags cost significantly more than passive RFID tags. Passive tags can cost as little as a few cents (and you can even print them yourself). Active tags start at a few dollars (if bought in bulk) and can cost as much as $25 or even hundreds of dollars. In addition, the lifespan of an active RFID tag is typically only as long as its battery life (unless they have replaceable batteries, which is unusual in RFID tags). With typical wear and tear, a regular passive tag can last up to 20 years. It depends on what the tag is encased in and the environment. Because of the battery, active RFID tags typically only last three to five years.
Tag size and attachment method
Because active transmitters are significantly larger and heavier, you can’t attach them reliably with adhesives — you have to use screws, zip ties, or another robust solution.
You need to make sure they’re securely fastened to the objects. With more points of failure, excess shaking could potentially shorten the lifespan of the tag. Passive RFID tags are small, lightweight, and very thin. They can easily fit into plastic stickers but can be encased in more robust materials if required. Which approach you choose depends on the environment in which you plan on using the tags. A metal casing might make sense if you want to use them as asset tags on outdoor equipment. For most other uses, epoxy or adhesives will do the trick.
Monitoring in real time vs. activation by scanning
Because an active tag has a battery source and its own memory chips, it can monitor processes in real time, while a passive tag is only activated by scanning. So, an active beacon tag could report, for example, location or temperature to your systems.
The middle-ground: semi-passive RFID tags
Semi-passive RFID tracking combines parts of the two different types of RFID tags. It has an internal battery, an RFID antenna, and data chips but no separate powered transmitter. Instead, it uses the battery to power the memory and chip so the antenna can use all the captured energy for its backscatter response. The signal range is lower than active tags, but with a battery-powered memory, it does make real-time monitoring and sensors possible, provided a scanner constantly pings it.
Main use cases for active RFID
Now that you know what sets active RFID apart, let’s talk about what businesses typically use it for.
Real-time location tracking of crucial assets
Active RFID lets you know exactly where in a larger building certain assets are. With active tags, these are often large-scale and expensive — shipping containers, maintenance equipment, and the like. It makes a lot of sense in the world of logistics. Quickly locating and identifying the right container makes life much easier for everyone involved. But of course, companies outside that industry can also find uses for it. If you have crucial assets you want to monitor in real time, active RFID tags may be a good idea.
Vehicle tolling on toll roads or ferries
When a person passes an automatic gate to get on the subway, passive RFID is enough. They can tap the card against (or at least move it toward) a scanner. However, the range is no longer sufficient when you increase the scale to include a vehicle. But RFID is perhaps the most convenient system for automatic gates. So, most modern automatic toll systems rely on active RFID tags instead. If your city has an automated toll system for toll roads in the area, you may already be using it. It’s typically a plastic box you can stick to inside your windshield. Approaching the toll gate in the automatic lane will trigger the tag and automatically open it (as long as your tag is valid).
Large-scale warehouse management
Actual position tracking makes life a lot easier for warehouse workers like pickers. It can help them find specific items they need to find and package. It eliminates a lot of the guesswork and helps your staff work more effectively. That makes the fulfillment process smoother and less prone to mistakes during shipment. Plus, warehouse pickers are injury-prone because of all the walking they do. If you can reduce needless walking, that’s also good for your employees’ health.
Main use cases for passive RFID
Passive RFID is favored for use cases like inventory management, access control, and animal identification.
Access control — automatic locks
You probably remember hotel key cards with holes punched through them if you're old enough. The electronic revolution first replaced these with magnetic strip cards — like your old credit cards. Today, these have been replaced with RFID cards in most hotels. You may also have an RFID-powered key if you live in an apartment complex with an automatic locking system.
Asset tracking — check outs & check ins
If you don’t need to track the location of your assets in real time, passive RFID can be more than good enough. For example, you can use passive tags to power an asset management system for lending out equipment. This is one of the main use cases for RFID in education.
Passive RFID tags are also popular for managing inventory. Because they let you scan items at a distance, you don’t need to rely on your staff. Many companies automatically scan inventory that enters a warehouse. For example, you could install a scanner on the conveyor belt that takes in packages from trucks.
Because of the long lifespan and small size of passive RFID tags, they’re also used for animal identification. RFID is integral in modern animal sciences and often in reuniting pets and owners after they get lost.
You can also leverage RFID technology for tracking the results of races more accurately. It’s now used in various sporting events around the globe, including cycling and long-distance running.
Last, near-field communication (NFC) is a subset of RFID technology that has revolutionized contactless payments over the past few years. The technology in modern credit cards and smartphones lets you pay without swiping your card. Essentially, it’s RFID but intentionally short-ranged to avoid security issues.
Set up your RFID tracking system today
The main differences between active and passive RFID are range and real-time tracking. Which is best for your company depends entirely on the use case. For larger, more valuable assets, active transponders are a good idea. Passive tags with a robust asset-tracking system are more than enough for basic asset tracking. And that’s where RedBeam comes in. Our cloud-based asset management system fully supports the industry-leading handheld scanner (RFID and barcode compatible) Zebra TC52. Together, we make it easy to track all the movements of your assets across locations. If you want better control over your assets, sign up for a 30-day free trial of RedBeam today.