The Foreign Service Journal, December 2005

F O C U S 32 F O R E I G N S E R V I C E J O U R N A L / D E C E M B E R 2 0 0 5 RFID is a generic term for technologies that use radio waves to automatically identify people or objects. Radio frequency identifi- cation technology uses the same electromagnetic radiation spectrum that radios use to transmit. The basic RFID system comprises a transponder, a reader and an antenna. Data are stored in a transponder device called a tag. Current tags, depending on application, can hold up to two kilobits of data. Tags can be read-only or read/write. A radio frequency signal is transmitted from the reader to a transponder that passes within range of the reader’s antenna. Unlike the ubiquitous bar code or the magnetic strip on a credit card, the RFID tag does not need a clear line of sight in order to be read. Instead, data in the tag is communicated via a radio signal. The signal is stimulated by a reader, which triggers the data in the tag to “ride” the radio wave back to the reader, where the data is captured and authenticated by a backend computer system. This tag is called a “passive” tag as the data is plucked by an external force. By contrast, an “active” tag relies on its own internal battery to sup- ply energy and send the data to the reader. Active tags are more expensive than passive tags. The Department of Defense is planning on incorporating global positioning technology with active transponders to be able to track in real-time where shipping containers of supplies are around the world. The type of RFID tag helps determine the read range, or how far away the data on the tag can be read. The source of power is anoth- er factor. Antenna size, too, is part of this determination, but the size and type of antenna are mostly functions of the operating fre- quency used. How It Works Frequency range Frequency type Read range Memory Comments 2.45 GHz Microwave 2 meters max Less than Silicon technology is in its infancy 1 kilobit for this frequency. 300 MHz to 3 GHz UHF Can be 6 meters 1 kilobit Sends faster and further than lower (typically 866 to or more frequencies. Spectrum use varies 960 MHz ) Ultra High Frequency by country. (Europe uses 868 MHz for UHF; the U.S. uses 915 MHz. Japan prohibits the use of UHF spectrum for RFID, but may open the 960MHz portion.) 3 to 30 MHz HF 1.5 meters at best 256 bits but Used for smart cards. (usually 13.56 MHz ) for high-end additional data Sometimes called “proximity” cards. High Frequency readers memory available today 30 kHz to 300 kHz LF 1 meter at best 64 bits to 1,360 Globally available frequency. bits; larger Low frequency allows tags to be read Low Frequency possible. through watery substances — the only technology that allows for this. A Brief Primer on the RF Spectrum To make radio waves, an alternating current is sent to an antenna, creating an electromagnetic field. The portion of the electromagnetic radiation spectrum used for wireless broadcasting and communications is from nine kilohertz to thousands of gigahertz. Still higher frequencies make infrared, visible light, ultraviolet, X-rays and gamma rays possible. To see the full-spread spectrum-usage allocation for the U.S., the National Telecommunications and Information Administration (U.S. Department of Commerce) has a nifty chart at http://www.sss-mag.com/pdf/freqchrt.pdf. Other countries allocate the use of spread spectrum differently. For the ultra-high-frequency RFID tags being used for sup- ply chain applications, the U.S. uses 915 megahertz. Japan prohibits the use of this frequency. Europe prefers 868 MHz. Consequently, the chance of reading these tags from one port to the next is not quite as easy as RFID advocates in the sup- ply chain business would like. This is one reason why RFID is still considered an emerging technology. China, as with many issues in today’s commerce, holds the trump card. With so many products coming from China, RFID tags must be applied that will meet frequency allocation regulations there and elsewhere around the world. Biometric passports do not encounter this problem as they are subject to standards set by an international organization, the International Civil Aeronautics Organization.