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5 Facts: Active RFID Technology and Real-Time Location Systems

5 Facts: Active RFID Technology and Real-Time Location Systems

Clare French
November 13, 2020

When it comes to tracking and monitoring assets anytime, from anywhere, the rush is on to implement an indoor positioning solution that incorporates active radio frequency identification (RFID) into real-time location system (RTLS) technology.

Why? Because active RFID is indeed durable and reliable, with a relatively long read range and robust data storage capacity. On top of that, it’s generally affordable and requires little to no human intervention.

Put simply, RFID is a form of wireless communication that uses low-power radio frequency waves to receive and transmit data. And while there are two basic types - passive and active RFID - we will focus our discussion primarily on the latter, given its greater versatility for real-time location tracking.

Of course, before investing in any technology, it’s always a good idea to learn more about it. So, to get you started, we have compiled a list of five interesting facts about RFID.

1) RFID technology claims a storied history that traces its roots back to the advent of radar technology during World War II.

Although the concept of radio waves emerged in the 1800s with the first theory on electromagnetic energy, RFID technology first hit the scene during World War II with the use of radar to warn of planes approaching from miles away. But in its earliest form, this technology had no way of identifying who these planes belonged to.

Determined to conquer this challenge, the British launched a secret research and development project that resulted in the first active identify friend or foe (IFF) system. Much like today’s RFID technology, it used radio wave transmission to identify friendly aircraft - a trailblazing invention that is still used by military and civilian air traffic control operations.

Moving forward, the 1950s and 60s saw more than a few advances in radar and radio frequency communications systems, including research around using RF energy to remotely identify objects. And in 1973, American inventor Mario Cardullo allegedly received the first U.S. patent for an active RFID tag with rewritable memory.

At around the same time, the Los Alamos National Laboratories began work on a system for safely and securely tracking the transport of nuclear materials - an invention that was reworked for tracking cattle, at the request of the U.S. Department of Agriculture.

These developments paved the way for employing RFID technology throughout the 1980s and 90s to accomplish such remote activities as collecting road tolls and monitoring railroad cars.

As the Internet of Things (IoT) began to take flight in the late 1990s, so did the pervasive use of active RFID for real-time locations systems, with more than 1,000 patents submitted by 2000. And according to Zion Market Research, the worldwide RFID equipment market is expected to boom, reaching more than $25 billion USD by 2022.

Related Reading: Asset Location Technologies and The Selection Process

2) While active RFID systems may differ in terms of device types and complexity, they all have at least three hardware components: readers, antennas, and tags.

The best way to understand how an active RFID system works is to think of its hardware components within the context of the human body.

Active RFID Readers

The reader - or interrogator as it is sometimes called - is the brain of the operation, in that it transmits and receives radio waves to communicate with an active RFID tag.

In doing so, it typically uses one or more antennas, along with a software application - commonly referred to as middleware - that transfers information from the reader to the system where it is processed. For the most part, RFID readers come in one of two distinct form factors: fixed and mobile.

As their name implies, fixed readers remain in one location, where they are usually mounted on walls, into portals, or on some other structure that is suitable for the read zone.

Because they generally need external antennas to accurately read active tags, they incorporate external ports for connecting one or more additional antennas, depending on the required area of coverage.

On the other hand, mobile RFID readers are notably compact, handheld devices, in which the antenna is either integrated or externally attached. Known for their flexibility, they can be mounted or carried pretty much anywhere, while still communicating with a host computer or smart device.

Active RFID Tags

Battery-operated tags serve as the heart of any active RFID system. When affixed to an object, they continuously broadcast their own signals - much like the heart pumps blood through the body to keep its organs functioning.

That said, active tags use these signals to track the asset’s location in real time, while recording information at very high speeds - which is why they work especially well for monitoring valuable assets on the move.

As it stands now, these tags come in a variety of sizes and shapes and typically have a battery life of a few years. They also have a long read range (more than 300 feet); do not require line of sight; and can generate data beyond simple positioning, such as ambient temperature and humidity. But on the downside, the cost can vary greatly from around $5 up to as much as $20 per tag.

Active RFID Antennas

And finally, RFID antennas are analogous to the body’s arteries and veins that carry blood to and from the heart. With that in mind, they are used for transmitting the reader’s interrogation signal to “wake up” the tag, which then sends a unique identification signal back to the reader via the antenna.

Antennas come in different sizes and designs, depending on a variety of factors. For starters, environmental conditions (temperature and/or humidity levels) are key, as is where the antenna will be mounted (indoors or outdoors). Likewise, read range is important. For example, by increasing the size of the antenna, you can lengthen the read range.

3) There are three types of active RFID: beaconing, transponding, and intelligent.

Active RFID comes in three distinctive types, which, in turn, lend themselves to different use cases. Here are the basics of each type...

Beaconing Technology

The most common type by far, beaconing RFID is a relatively simple system, in which battery-powered tags beacon an encrypted identification message at a speed of somewhere between every 100 milliseconds to every five seconds.

For the most part, it uses Bluetooth Low Energy (BLE) technology, given its low cost and power efficiency - although there are a few proprietary technologies on the market that work just as well.

As costs go, tags range in price from $5 (for basic beaconing) to $100 (for the heavy duty variety), while the expense associated with data transmission varies, depending on the reader state. Beaconing RFID systems are most cost-effective when the reader transmits data only when the tag moves, which lowers the amount of information being broadcast.


Automated toll collection systems are a great example of transponding active RFID. In essence, these systems run off of a passive reader, an antenna, and an active, battery-powered transponder or tag affixed to the vehicle that does not transmit, but does receive radio signals.

So when the car pulls into a collection lane, the passive reader emits a signal that “wakes up” the active transponder, which then broadcasts a unique serial identification number to a centralized computer where it is stored to record the payment.

This hybrid functionality not only extends battery life to around 10 years or more, it also requires minimal infrastructure. And while this type of active RFID has become the toll collection standard, it can also work for other asset location solutions that don’t require long read ranges or constant tracking.

Intelligent RFID

Intelligent RFID is also a hybrid of sorts that combines beaconing and transponding active RFID. Under this scenario, intelligent active RFID tags are designed to wake up at established intervals, scanning their environment for nearby fixed reference point beacons, which they use to calculate their locations (the “intelligent” function). Then the tags send this data back to the reader.

These intelligent active RFID systems are significantly more cost-effective than beaconing RFID for a few compelling reasons. (In fact, at Link Labs, we were so impressed with these benefits that we converted our AirFinder real-time location system from beaconing to intelligent RFID as a way to lower the cost for our customers.)

For starters, these systems are more location-accurate and less infrastructure-heavy, while also requiring little to no IT integration. Likewise, the only data they transmit through the backend are asset location and condition changes. Naturally, the reduced data burden greatly increases the tag’s battery life.

4) An RFID system transmits at three basic frequencies within the electromagnetic spectrum: low, high and ultra-high.

Low Frequency (LF) RFID

These RFID systems operate at a general frequency range of between 30 and 300 KHz, with a read range of as much as 10 centimeters.

That translates into a particularly short read range, limited memory storage, and a slower data transmission rate than those systems with higher frequency transmissions. On the other hand, however, LF RFID tags perform better around metal and/or liquids.

At a relatively low average cost per tag - $0.75 to $5.00 - low-frequency RFID is used primarily for animal tracking (think of sprawling ranches) and access control (such as key cards); although it can be deployed for other applications that don’t require a longer read range.

High Frequency (HF) RFID

With a general frequency range at between 3 and 30 MHz and a read range of around 30 centimeters, HF RFID systems lend themselves well to electronic ticketing and payment transfer, as well as other types of smart cards.

For example, Near Field Communication (NFC) technology, grounded in HF RFID, is often used for such common applications as hotel key cards. As a side note, we’ve written more on the differences between RFID vs. NFC for asset location.

What’s more, like LF, HF uses magnetic coupling to communicate between RFID tags and readers. So by relying on this as their power source, HF tags generally keep functioning for the lifespan of their application, unless damaged by wear and tear.

And to make them even more attractive, these tags are also relatively inexpensive at around $0.35 to $10.00 per tag, and typically small in size.

Ultra-High Frequency (UHF) RFID

UHF active RFID systems have a frequency range between 400 MHz and 3 GHz, with much higher read ranges of 30 to 100+ meters, along with faster data transfer rates. In addition, they have a fairly low infrastructure cost and a large memory capacity.

Equally important, their tags are powered by internal batteries and proactively beacon at predetermined intervals, which are detected by RFID readers and passed on to the host system for processing.

On the downside, however, UHF RFID tags cost more at an average price of $25 to $50 per tag, and are pretty sensitive to interference from metals, liquids, and electromagnetic signals - although innovative design is mitigating some of these issues. At the same time, because they are battery-powered, these tags have a limited lifespan of three to five years.

Active UHF RFID applications are commonly used for tracking mobile assets (e.g. cargo containers, large equipment, and vehicles), as well as assets like construction tools and materials that are stored in large areas, such as laydown yards.

5) RFID technology has come a long way over the past two decades in form, function, and application.

As IoT devices become increasingly ubiquitous, active RFID technology is growing ever more sophisticated, particularly with respect to real-time asset tracking and tracing. In fact, by maintaining asset visibility 24/7/365, organizations of all types and sizes are not only improving their bottom line, they are also saving lives, mitigating hazardous events, and reducing liabilities.

That said, there have been more than a few advancements in active RFID technology over the past two decades, including:

  • Active RFID tags that incorporate innovative sensor technologies for monitoring such environmental factors as temperature, humidity, and vibration
  • Increasingly small smart RFID tags that are also thinner and lighter, with more memory
  • Less costly RFID readers with increased read rates (1,000 to 1,200 tags per second) and sensitivity, along with more connectivity options for transferring data
  • A variety of specialized antennas, with less weight and bulk
  • Cloud-based applications and services for managing data flow, thereby creating solutions that require little or no IT support
  • Real-time location systems that are far more power- and data-efficient, with fewer infrastructure requirements.

Of course, with all of these advancements, active RFID is being deployed in innovative Bluetooth RTLS solutions - like AirFinder - across multiple industries to manage a variety of valuable assets. Here are a few examples:

RTLS for Healthcare and Emergency Management

Hospitals are using RTLS solutions that leverage a combination of active RFID tags and BLE sensor beacons to greatly improve patient care, by keeping track of medical treatment equipment location and condition as it moves between rooms and floors.

And with the introduction of our AirFinder SuperTag - which provides seamless visibility both indoors and out - we can now offer the same benefit for mobile field hospitals that furnish much-needed emergency medical support in disaster zones and during major epidemics.

Hospitality Industry Safety

Given the need to keep hospitality employees safe at all times inside the facilities where they work, AirFinder blends RFID technology with Bluetooth and ultrasound to produce lightweight, easily wearable hotel panic button systems. Designed to run off a simple plug-in device in each room, they quickly send a distress signal, which registers the employee’s exact location.

Cargo Tracking in Transportation Hubs

While there are many use cases for RFID RTLS solutions in transportation hubs, some of the more popular involve tracking the location of a critical piece of cargo, as well as monitoring large lots of pallets on the move. Likewise, these solutions can be deployed to maintain chain of custody, as well as ensure that climate-sensitive assets are not being moved into areas where high temperatures or humidity could damage them.

Manufacturing Asset Management

Like the transportation industry, manufacturing operations of all types and sizes are implementing active RFID RTLS with greater frequency for any number of critical functions.

To be sure, they are employing these solutions for manufacturing asset management and tracking the real-time location of both equipment and employees in and through the building. The same goes for pallets used for storing raw materials and other movable inventory. Likewise, they are monitoring environmental fluctuations in temperature and motion that might have an impact on expensive equipment.

Final Thoughts…

As an integral component of IoT, active RFID technology has definitely made RTLS solutions easier, cost-effective, and more reliable. But as you might imagine, these systems will continue to improve going forward, as the RFID market is growing at an exponential rate. So while we hope that you now have a basic understanding, please do not hesitate to contact us for more information on all things RFID.


AirFinder - Asset Location Technologies & The Selection Process

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