What is RFID?
RFID is the acronym for Radio frequency identification; it belongs to the family of automatic identification and data capture. We can store a serial number that identifies a person or object, and perhaps other information, on a microchip that is attached to an antenna which is collectively called as a RFID tag or RFID Transponder. The antenna enables the chip to transmit the identification information to a reader. The reader converts the radio waves reflected back from the RFID tag into digital information that can then be stored in a computer.
What transponder is made up of?
RFID tags are small microchips with memory and an antenna coil. When a RFID tag receives a query, it transmits its unique ID and perhaps other information back to the reader.
What are passive, semi-passive and active RFID tags?
An active RFID tag uses an internal power source, such as a battery, within the tag to continuously power the tag and its RF communication circuitry. Low-level RF signal of the reader is sufficient to activate the, and the tag can generate high-level signals back to the reader. Active RFID tags are to be continuously powered and are normally used when a longer communication range is desired.
A passive RFID tag depends on RF energy of the reader to power the tag and its RF communication circuitry. Passive RFID requires strong RF signals from the reader/interrogator. High-level RF signal of the reader is required to activate the tag, and the tag can generate high-level signals back to the reader. Passive RFID tags are normally used when a shorter communication range is desired.
A semi-passive RFID tag uses an internal power source to monitor environmental conditions, but requires RF energy from the reader similar to passive tags to power a tag response. Semi-passive tags use that internal power source (battery) for monitoring environmental conditions (temperature etc).
What reader is made up of?
RFID read-only readers Read only readers query the unique ID from the RFID tags.
RFID read-write readers They are usually referred as Interrogators or encoders, these readers read and also write information to the RFID tags.
Communication range for a RFID tags?
RFID tag communication range roughly is:
LF tags: < 300 cm
HF tags: < 1m
UHF tags: < 10m
UHF tags (active): > 100m
Microwave tags: < 3m
ISO/IEC RFID Standard
ISO/IEC 14443: Standard for proximity cards (communication range around 10cm)
ISO/IEC 15693 : Standard for vicinity cards, smart tags (communication range around 1.5m)
EPC Global RFID Standard
EPC Class 0 : Identity Tags (Read only)
Common applications for RFID?
EPC Class 1 : Identity Tags (Write Once / Read Many)
EPC Class 2 : Higher Functionality Tags (Read / Write)
EPC Class 3 : Semi Passive Tags (Read / Write with battery power to enhance range)
EPC Class 4 : Active Tags (Read / Write active transmitter)
UHF Class 1 Gen 1 : C1G1 at 860-930MHz, is not backward compatible with Class 0.
UHF Class 1 Gen 2: C1G2 at 860-960MHz is merging with the C1G1 and Class 0 standard.
LF typical applications: Access control, Animal identification, Event ticketing.
HF typical applications: Library management, pharmaceutical counterfeit, and etc.
UHF typical applications: Access control, distribution logistics, airline baggage handling value, and etc.