RFID is much like a wireless bar-code system. You only aware of them when you leave Wal-Mart and the RFID tag on your favorite brand of toothpaste is not properly deactivated by the check-out girl, causing you to accidentally set-off the security alarms.
There are various styles of RFID systems that come in two distinct flavors: Passive and Active. Passive RFID systems generally use one of two specific frequency bands to transmit wireless data: 125kHz and 13.5MHz. These are close-proximity systems, where the RFID Tag and Transceiver need to be within inches to several feet in order for them to communicate with each other. Passive systems are used primarily for security pass access, tracking package contents, anti-theft devices, and currently gaining favor banking market as a replacement for magnetic card-stripe readers for credit cards and ATM’s. These systems are called Passive because the RFID Tag has no power source; it derives its transmit power from the received RF signal from the RFID Transceiver (Reader).
Active RFID systems use higher frequency bands. Typically, these range from 800-900MHz and on up to the 2GHz range. They are called Active because the RFID Tags contain a separate power source, which allows for the RFID Transceiver and Tag to be separated by larger distances. One of the more common uses for Active RFID Systems is in the Toll Booth market. Users can subscribe to a service that allows automobile owners to travel through Toll Booth’s without having to stop and drop a few dollars into a bucket. The Active RFID Transceivers scan forward into oncoming traffic, detecting drivers with an Active RFID Tag attached to the inside of their windshield. When the RFID Tag detects it is being scanned, it sends back the users ID. The RFID Transceiver and Tag then pass small amounts of information between each-other in an attempt to verify the identity of the user and if accepted. At the end of the month, the user gets an itemized list of the number of times they have driven through the toll-booth, where the user can then pay the bill at a more convenient time.
RFID technology has even found its way into the hospital as a replacement to the current bar-code system. With surgery error killing thousands of people each year, every attempt to reduce those numbers are welcome sights. Here, RFID tags are attached like a bandage to each patient. Nurses and doctors carry with them portable RFID scanners, which read the RFID tag information, cross-referencing the RFID tag with the hospital’s database.