RFID uses radio signals to identify people and objects without physical contact. There are two main types of RFID tags: passive tags, which have no power source and are activated by the reader, and active tags, which require a power source like a battery. Passive tags are commonly used for retail because they have indefinite lifespans and can be made very small. A passive tag consists of an antenna and microchip that are powered and communicated with by an RFID reader.

1. • RFID stands for Radio Frequency Identification. By
means of radio signals, RFID can realize a
contactless and unique identification of persons
and products on a short range.
• To do this, RFID utilizes so-called tags: electronic
labels in which the unique information is saved
digitally. This digital information can be read with a
special reader unit.
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2. Passive RFID tags
• Passive RFID is of interest because the tags don’t require batteries
or maintenance.
• These tags also have an indefinite operational life and are small
enough to fit into a practical adhesive label.
• A passive tag consists of three parts: an antenna, a semi conductor
chip attached to the antenna, and some form of encapsulation.
• The tag reader is responsible for powering and communicating with
a tag.
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3. Active RFID Tags
• Active tags require a power source—they’re either
connected to a powered infrastructure or use energy stored
in an integrated battery.
• Batteries make the cost, size, and lifetime of active tags
impractical for the retail trade.
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5. • Two fundamentally different RFID design approaches exist
for transferring power from the reader to the tag:
1. magnetic induction
2. electromagnetic (EM) wave capture
• These two designs take advantage of the EM properties
associated with an RF antenna—
the near field and the far field.
• Both can transfer enough power to a remote tag to sustain
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6. Near field RFID
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7. Far field RFID
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8. Advantages
• No line of sight required
• Long range identification feasible
• Multiple tags can be detected (nearly)
simultaneously
• Operates in harsh environments
• Memory to store data on object
• Possibility to integrate sensors
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9. Application
• Keyless entry
• Electronic Product Code (EPC)
• Proximity cards
• Security device
– Bookstores
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10. • Human implant ( human identification )
• Animal implant ( animal identification)
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11. References
• K. Finkelzeller, The RFID Handbook, 2nd ed.,
John Wiley & Sons, 2003.
• M. Weiser, “The Computer for the 21st
Century,” Scientific Am., vol. 265, no. 3, 1991,
pp. 94–104.
• R. Want, “Enabling Ubiquitous Sensing with
RFID,” Computer, vol. 37, no. 4, 2004, pp. 84–
86.
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