By Jay Palter | March 26, 2020
Determining which wireless tracking technology is the best for your needs can be difficult. There are so many different products on the market today, and every one seems to have its own special features and an acronym for a name. The difference between active vs. passive RFID is one common source of confusion.
We want to help clear that up. Determining the right RFID technology for your workplace should be easy once you understand how the two systems work.
Active vs. Passive RFID: The Same Basic Technology with Different Capabilities
All RFID tracking systems use some combination of tag and reader hardware, and both RFID technologies are capable of delivering good ROI on people and asset tracking. But the similarities end there. The transmission, frequency and read range, tag size, lifecycle, attachment method, and cost all differ. Here’s how:
Active RFID systems use battery-powered tags that push their stored data to readers. Passive RFID systems pull data from unpowered tags at close range.
Frequency and Read Range
RFID systems can use several different frequency bands. The band determines data tag read ranges, as well as the materials that the RFID signal can transmit. Passive RFID systems typically operate in one of three bands:
- Low Frequency (LF) systems operate between 125 and 134 KHz. They have a short range of up to four inches, but tag reading is incredibly reliable and not disrupted by water or metal objects.
- High Frequency (HF) systems operate at 13.56 MHz. They have a longer read range of up to three feet. HF signals can pass through water and soft tissue, but can be blocked by metals.
- Ultra-High Frequency (UHF) systems operate between 865 and 960 MHz. They have a read range of up to 30 feet. While read times are very fast, this band is easily disrupted by water, soft tissue, and metals.
Active RFID systems typically use either 433 or 915 MHz frequencies. Both offer a reliable read range of up to 100 yards. 433 MHz is used more often because its signals better pass through water, soft tissue, and metals.
Passive RFID tags can be very small. Two of the most common form factors are flat tags, which can be as small as a fraction of an inch in size, and two-inch keychain-sized tags.
Active tags vary more widely in size because they often come integrated with other electronics. Typical models range from one to four cubic inches.
Passive tags are unpowered and solid-state, which means they have an unlimited lifecycle as long as they stay intact. Because they are so durable, some providers offer a lifetime guarantee.
Active RFID tag lifecycles are usually determined by their batteries, which last three to five years. Higher operating frequencies and constant use shorten their lives.
Passive tags can be glued to or embedded in a wide range of materials. Real Time Networks has even embedded them in kitchen knife for airport food prep security. The larger housings of active RFID tags usually need to be clipped, glued, or bolted to the assets they track.
Today you can expect to spend between $0.10 and $0.50 per passive RFID tag. Active RFID tags typically cost between $5 and $15, but like with their size, cost will also vary widely depending on what other electronics need to be integrated.
How to Choose the Right RFID Tech
In general, passive RFID works best when you can place assets close to readers in a controlled manner. For example, passive RFID is likely the best choice if you want to do transaction logging, such as in a key management system. However, if you need to track moving objects at a distance in larger, complex environments, then active RFID tracking probably makes more sense.
There are also a few special considerations you might need to make when deciding between active vs. passive RFID:
Is RFID Regulated in Your Jurisdiction?
UHF passive RFID is coming under increased regulation. Check this overview of global UHF regulations assembled by the standards group GS1 to see what might apply in your area.
Do You Need to Track Assets in Harsh Conditions?
The solid-state design of passive tags makes them incredibly durable. They are well-suited for outdoor or harsh indoor conditions. But their short read range might be a problem. Active tagging will scan much more reliably in those settings, but they will require ruggedized housings to keep the battery and other electronics protected.
Do You Need Tracking in a High-Temperature Environment?
Will your tagged assets need to pass through a sterilization chamber? This is increasingly common in healthcare asset tracking. Solid-state passive RFID tags with no batteries are usually the only option in such cases.
The Right Tool Is Out There
RFID tracking systems can perform in a wide range of conditions. You should now be in a better position to decide whether active or passive RFID technology is right for your needs.
If you want to learn more about evaluating key tracking technology, take a look at our Top 10 Purchasing Checklist for Key Management Systems.
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