What is (RFID) Radio Frequency Identification?
Radio Frequency Identification is a technology that uses Radio Frequency waves to interrogate or read objects known as transponders or tags. Each tag always has a Unique Identification Number (UID) stored in bits in the tag memory that is transmitted to the reader when the Tag is Read. In addition to the UID there may be other information stored in the tag memory. The technology allows for reading of tags from physical contact to beyond the line of sight of the reader. A simple RFID system consists of a reader with a cable attached to an antenna and a tag that is read(interrogated) by the reader.
Radio Frequency (RF) Basic Terminology
Radio Frequency signals are a form of electromagnetic wave consisting of the same radiation as light, ultra-
The frequency that a radio frequency identification (RFID) system operates is called a “carrier wave” or "carrier frequency".
RFID systems operate on a number of frequencies. Some of the common RFID Frequencies are
• 125 kHz. Also known as Low Frequency (LF)
• 134.2 kHz. Also known as Low Frequency (LF)
• 13.56 MHz. or High Frequency (HF)
• 433 MHz. Ultra High Frequency
• 868 MHz. – European – Ultra High Frequency (UHF)
• 915 MHz. – Ultra High Frequency (UHF) -
• 2.45 GHz. Microwave Frequency (SHF)
• 5.8 GHz. Microwave Frequency (SHF)
433 MHz, 2.4 GHz and 5.8 GHz are active technologies with long range capabilities of between 50 meters and 500 meters or more. Due to the nature of these technologies we will not really discuss them in these courses.
Many of these belong to the Industrial, Scientific and Medical (ISM) radio bands which were originally reserved internationally for the use of RF energy for industrial, scientific and medical purposes other than communication. The ISM bands typically do not require any licensing to operate in these bands. Note: some countries will not allow some ISM bands at all.
Antennas are tuned to resonate only to a narrow range of carrier frequencies that are centred on the designated RFID system frequency. This means that a system with a carrier wave of 915 MHz.(centre of 902 ~ 928 MHz.) will not read a tag at 13.56 MHz., 125 kHz. Frequencies or 2.45 GHz.
However it may be able to read an 868 MHz. tag if the tag is EPC Gen 2.