1. Part 1: Introduction to the RFID Industry
I’m the editor of RFID Journal. I founded the journal about three and a half years ago believing that RFID was going to be part of this wireless revolution. At the time, very few business people had even heard of RFID, and it was nowhere on their radar, but there was some work going on at Wal-Mart. I thought [RFID] was going to be very, very powerful and that’s why I started the journal. Today we are the leading publication in this area and we’ve got about 150,000 people that come to our Web site every month.
“RFID” is an often misunderstood technology because it’s this very broad definition and covers a whole bunch of things. People tend to focus on one thing and call that “RFID” and they leave out everything else. RFID, broadly speaking, is the ability to identify something remotely using radio waves, and there’s a lot of different ways to do that. You’ve got active tags, which have batteries, and those are probably most familiar to consumers because they’re used in the toll collection system. A drive-up reader sends out a signal [that] powers up your transponder on your windshield, and a battery-powered device broadcasts to the reader your unique ID.
A semiactive tag or a semipassive tag—definitions are pretty loose in the RFID world—is a tag that has a battery but doesn’t use it to broadcast. Instead it uses [the battery] to power the chip and perhaps power an onboard sensor, and that gives you a little bit of extra read range because the power could be concentrated, reflecting back the signal, giving better performance.
And, of course, lastly there’s passive [tags] and that’s what most people talk about when they talk about RFID. “Passive tag” simply means a tag without its own power source, so it gathers energy from the reader and reflects back a signal to the reader.
Figure 1. Example of an RFID tag
There are different kinds of passive tags: there are low-frequency tags that are used in cattle tracking, which is one of the first applications. There are some other short-range applications where [tags] are used tracking vials in a lab, for instance. High-frequency tags were the next evolution in RFID. Probably, I would say, at least 75% of you right now have an RFID tag on you. That’s a guess. If you have a key chain with a plastic thing on it, that’s an RFID tag, that’s a 13.56 MHz tag. That’s why the plastic is there—to hold the tag. You stick that key into the ignition, and the reader in the steering column communicates with that tag. If it doesn’t get the right ID, your car doesn’t start, which prevents the unauthorized copying of tags. You may also have an access-control card to get into your building—that’s also a 13.56 MHz RFID tag.
Finally, [ultra high frequency] (UHF) is the most recent incarnation of RFID. UHF uses (in the United States) 902 to 928 MHz. That’s been adopted recently, within the last few years, and UHF has been catching on.
Then you’ve got microwave—2.5 to 2.45 GHz. Those systems are typically the active systems such as real-time locating systems where you broadcast the signal.
This concludes the first part of a six-part tutorial series. To see the complete list of topics, view the RFID Tutorial Main Page.
2. Solution for Testing RFID Readers (Interrogators) and Tags
- Vector Signal Generator
- RF Signal Analyzer
- PXI Chassis and Controllers
- LabVIEW Graphical Programming Environment