“Passive RFID are tags that require an external stimulus in order to be read. So it’s a chip with an antenna. And when you apply a radio signal to that label, you get what they call the backscatter, or a reflection, off that signal, and then you read that reflection and that’s how the passive RFID is read,” says Zahir Abji, president and CEO of Guard RFID Solutions. It’s inexpensive, he adds, running from several cents to several dollars for a tag or label. You’ll often see passive RFID tags on retail items.
Active RFID can be four to five times as expensive as passive RFID, says Richard Jenkins, vice president of marketing and strategic partnerships at RF Code, which specializes in active RFID. But despite the cost, he notes that several large companies, such as Bank of America and Thomson Reuters, started out with passive RFID and then switched to the active technology because it suited their needs better.
For example, passive RFID doesn’t do as well in a metal-dominated environment like a data center, because the RF waves bounce off the metal. “They are either not read well or not read at all,” says Jenkins.
Active RFID tags use batteries for power and to broadcast information via radio waves to readers in real time. “So any time one of our tags is in motion, it’s traveling every 10 seconds to a network of receivers, which then broadcast the location of that particular piece of equipment to the potential head end,” says Mohsen Hekmatyar, of Elpas (a division of Tyco), another company that sells this type of product. By contrast, passive tags only tell the company where the asset was the last time the system saw it.
Companies set up their RFID systems in a variety of ways. Steve Pisciotta of Remote Tracking Systems says his company often implements its v-track RFID system in fixed sites like airports, seaports, and military bases. He explains how it works: “We set up a series of base receivers throughout a facility…. So we create a wireless infrastructure around that facility,” he says. Then when a person “with one of our tracking devices is driving and walking around, every second it’s sending out a message that says, this is the tracking ID and this is where I’m located.”