An RFID transponder is a combination of an integrated circuit chip attached to an antenna.  Transponders have varying “read and write” functionality, power sources, operating frequencies and data capacities.

Read Only (R) – consisting of factory-programmed memory with permanently stored information, such as unique serial number or EPC code.  It can be read multiple times but may not be written to after manufacture.

There are three (3) read/write functionalities supported by RFID technology:

Write Once Read Many (WORM) – consisting of user-programmable memory with multiple read capability, but can be written to only once after manufacture.

Read/Write (R/W) – consisting of user-programmable memory with multiple read and write capability after manufacture.

Transponder Power Sources
The following power sources apply to RFID Transponders:

Active Transponders are equipped with a battery power source with a finite life span.  They cost more than Passive Transponders but have the benefit of a greater range of signal transmission and in some instances can support processing of data onboard.

Passive Transponders are powered solely by the RF energy emitted from the Interrogator.  They are smaller, lighter, and less expensive than Active Transponders, and have virtually an unlimited life span.  Their range of signal transmission is also shorter, limited by the RF energy emitted from the Interrogator.

Read and Write Functionalities
There are three (3) main categories of frequency supported by RFID technology:

Transponder Operating Frequencies

Low Frequency – (125 KHz – 139 KHz)

  • Typical maximum Read Range up to 4 inches

High Frequency – (13.56 MHz)

  • Typical maximum Read Range up to 5 feet

Ultra-High Frequency – (433 – 960 MHz)

  • Frequency and power varies by region of the world – Europe, US/Canada, Australia, Asia, Japan, etc.

  • 10-15 feet max read range on passive tags- open air

  • Centered around 915 MHz in the Americas

Microwave – (2.45 GHz and above)

  • Shorter read ranges than UHF (up to 4 feet)