RFID TECHNOLOGY

How does an RFID system work?
An RFID system consists of a tag made up of a microchip with an antenna, and an interrogator or reader with an antenna. The reader sends out electromagnetic waves. The tag antenna is tuned to receive these waves. A passive RFID tag draws power from the field created by the reader and uses it to power the microchip's circuits. The chip then modulates the waves that the tag sends back to the reader, which converts the new waves into digital data.

What is the difference between low-, high-, and ultra-high frequencies?
Just as your radio tunes in to different frequencies to hear different channels, RFID tags and readers have to be tuned to the same frequency to communicate. RFID systems use many different frequencies, but generally the most common are low-frequency (around 125 KHz), high-frequency (13.56 MHz) and ultra-high-frequency or UHF (860-960 MHz). Microwave (2.45 GHz) is also used in some applications. Radio waves behave differently at different frequencies, so you have to choose the right frequency for the right application.

How do I know which frequency is right for my application?
Different frequencies have different characteristics that make them more useful for different applications. For instance, low-frequency tags use less power and are better able to penetrate non-metallic substances but their read range is limited to less than a foot (0.33 meter). High-frequency tags have a maximum read range of about three feet (1 meter). UHF frequencies typically offer better range and can transfer data faster than low- and high-frequencies. But they use more power and are less likely to pass through materials. And because they tend to be more "directed," they require a clear path between the tag and reader. UHF tags could be another option. It is best to work with a knowledgeable consultant, integrator or vendor that can help you choose the right frequency for your application.

Do all countries use the same frequencies?
Most countries have assigned the 125 kHz or 134 kHz area of the radio spectrum for low-frequency systems, and 13.56 MHz is used around the world for high-frequency systems. But UHF RFID systems have only been around since the mid-1990s, and countries have not agreed on a single area of the UHF spectrum for RFID. Europe uses 868 MHz for UHF, while the U.S. uses 915 MHz. Until recently, Japan did not allow any use of the UHF spectrum for RFID, but it is looking to open up the 960 MHz area for RFID. Many other devices use the UHF spectrum, so it will take years for all governments to agree on a single UHF band for RFID. Governments also regulate the power of the readers to limit interference with other devices. Some groups, such as the Global Commerce Initiative, are trying to encourage governments to agree on frequencies and output. Tag and reader makers are also trying to develop systems that can work at more than one frequency, in order to get around the problem.

I've heard RFID can be used with sensors. Is that true?
Yes. Some companies are combining RFID tags with sensors that detect and record temperature, movement and even radiation. One day, the same tags used to track items moving through the supply chain may also alert staff if they are not stored at the right temperature, if meat has gone bad or if someone has injected a biological agent into food. RFID is not just for plastic card issuers.

In addition to printing photographs, text, and bar codes, ID card printing systems can encode personalized data onto magnetic stripes, smart cards, and proximity cards.

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