Active RFID vs. Passive RFID: Which Tags to Choose and When to Use Them
For decades, asset-heavy businesses have used radio-frequency identification (RFID) in the form of tags and labels to monitor and track their assets, yet the indecisiveness of choosing either an active RFID tag or a passive RFID tag has remained.
Using RFID Technology to Track Assets
With a global market share estimated to be worth $36.3 billion, businesses are recognising the importance of digitising their asset tracking processes. This has lead to a surge in the implementation of tracking technology and systems, such as an RFID tracking system.
As automated cloud-based tools like Asset Tracking Software become more accessible and affordable, asset-heavy organisations are reaping the benefits associated with tracking all forms of physical assets. Benefits such as building accurate asset registers, reducing replacements costs, and improving inventory management.
Among popular tracking technologies like GPS, NFC, Barcode, and QR Code, RFID is a system that can be traced back to the Second World War where it was used to identify and track enemy aircraft. Over the next 80 years, RFID technology evolved and became a main feature in the way businesses track, monitor, and manage their assets by using passive RFID and active RFID tags.
Today, RFID systems are used in multiple industries and processes including logistics, education, supply chain management, and manufacturing. One industry that has thrived using RFID tracking tools is retail. American retailer Walmart spent $500 million implementing an RFID system in 2004. While UK clothes retailer River Island increased their stock accuracy from 70% to 98% by deploying active and passive tags across stores and warehouses.
One advantage that RFID has over other tracking systems is the use of different types of tags. Each tag, whether passive RFID or active RFID, has various attributes that make either one ideal for different scenarios.
The Difference Between Active RFID and Passive RFID Tags
Although each RFID system can differ depending on the use of a passive or active tag, the required equipment remains the same; a tag, an antenna, a scanner/reader, and a digital database. Once in place, the process of tracking assets with RFID is broken down into four stages:
- Data is stored on a tag and attached to an asset
- An antenna identifies the signal of a nearby tag (passive or active)
- A reader connects to the antenna and receives the data stored on a tag
- The reader transmits the data to a database
A key variable that is interchangeable in this process is the tag. The two main types of tags to choose from are passive RFID tags and active RFID tags. Each tag offers its own unique capabilities when it comes to storing data and interacting with readers.
What is a Passive RFID Tag?
A passive RFID tag is a batteryless tag typically used in smaller-scale operations and tracking systems. Because a passive tag has no internal power source, it is instead powered by the energy transmitted from an RFID scanner. When compared side-by-side with their counterparts, passive RFID tags are generally a more utilised tag for businesses that have a large inventory of physical assets. This is due to their inexpensive cost and potential for a longer operational life.
Key points to remember regarding passive RFID tags include:
- They have no internal power source and are powered by a reader
- They have a lower signal range than active RFID tags
- Each one has a longer life expectancy than active RFID tags
- They are an inexpensive option starting at an average price of $0.08 per tag
What is an Active RFID Tag?
Whereas a passive tag has no internal power source, an active RFID tag comes equipped with its own battery and internal transmitter in the form of a beacon or transponder. This means that an active tag is able to continuously transmit signals to an RFID reader up to 150 metres away, depending on frequency levels. This makes the use of an active RFID tag popular among businesses wanting to track assets in real-time and build an accurate real-time location system (RTLS).
Key points to remember regarding active RFID tags include:
- They’re battery-powered tags that continuously transmit signals
- They are commonly used to transmit data in real-time
- Each one has a signal range of up to 150 meters
- They’re more expensive than passive RFID tags
How Active RFID Tags Work
When implementing an active RFID system to track assets, businesses require a reader, an active tag, and an antenna. Unlike a passive tag, which has no internal power source, an active RFID tag will feature a long-lasting battery. This allows it to continuously send signals and transmit data stored on a tag.
When to Use an Active RFID System
Active tags are more than likely to operate with an ultra-high frequency between 433MHz and 960MHz. This allows them to transmit data at a greater range and provide users with the ability to read data stored on a tag from up to 150 metres away. This makes an active RFID system a perfect choice for processes such as:
- Vehicle tolling
- Real-time location tracking
- Inventory management
- Asset management
As with most equipment, there are variations of active tags that are suited for multiple business tasks. An active tag can be either a transponder or a beacon, the latter sending data continuously every 3-5 seconds and the former taking a more efficient approach by sending data only when a reader is in range to conserve battery life.
As well as this, active RFID systems also operate on various frequency levels. Lower frequencies providing more penetrating signals that are best used with materials such as water and metals.
Advantages of Active RFID Tags
- Long data read ranges of up to 150 metres
- Significant data memory and storage capacity
- Advanced data capabilities
- Rugged and weather-proof active labels
Disadvantages of Active RFID Tags
- More expensive than passive RFID tags
- Tags will need replacing when battery life ends
How Passive RFID Tags Work
A passive RFID system consists of a reader, an antenna, and a passive tag. As the tag has no battery or power source, it consists of two components: an antenna and a microchip or integrated circuit (IC).
When to Use Passive RFID Tags
Instead of continuously sending data like an active RFID tag, passive tags will sit idle and wait until they receive a signal from a reader. With no power source, a passive tag’s energy is drawn from the radio-frequency waves that originate from a reader. These waves wake the tag’s IC and generate a signal back to the RFID system. This is also known as backscatter.
Similar to active tags, there are multiple variations of a passive RFID tag. Two of the most common types are called inlays and hard tags. Inlays provide the cheapest option for an RFID system and are typically attached to assets with adhesive. Whereas hard passive tags are rugged and made from materials such as plastic and metal. This makes hard tags essential for businesses with assets that operate in:
- High temperatures
- Adverse weather conditions
- Outdoor environments
As with active tags, passive RFID tags also work at various frequencies, too. Each frequency offers different read ranges, attachment options, and capabilities.
Advantages of Passive RFID Tags
- More affordable than active tags
- Have a long life expectancy
- Offer a vast range of tag options
- Small and lightweight
Disadvantages of Passive RFID Tags
- Have a low signal range of up to 5 metres
- Require a reader to power the tag’s microchip/IC
What About Semi-Passive RFID Tags?
Sitting directly between active and passive tags are semi-passive RFID tags. A semi-passive tag behaves exactly as a middle option should, by offering a mix of features taken from the capabilities of both active and passive tags. Semi-passive RFID tags feature:
- An internal battery as well as an antenna and microchip/IC
- A low signal range when compared to an active RFID tag
- Cheaper pricing than active tags
- Real-time tracking and sensor capabilities
- Shorter read ranges than active tags but longer read ranges than passive tags
Like an active RFID tag, a semi-passive tag has an internal power source in the shape of a battery. Typically small and eco-friendly, a semi-passive tag’s battery is used to improve data transmission and read ranges. Making them an ideal and cheap solution for using RFID tracking systems for environment and condition monitoring such as temperature-controlled transit.