D3.7 A Structured Collection on Information and Literature on Technological and Usability Aspects of Radio Frequency Identification (RFID)

Untitled TYPES OF RFID SYSTEMS

Types of RFID systems

The flow diagram in illustrates how some of the aspects of the RFID system are dictated through the choice of others. Conversely, some aspects are independent, and are selected based purely on the RFID system design criteria. Here we shall discuss the factors involved in the decision process of some of the main system aspects.

1. 1. 1. Frequencies and range

RFID systems can operate over a large range of frequencies (see ) although the choice of frequency depends on the mode of operation and the application. One of the main factors to consider is the range over which the RFID reader and tag can communicate with each other which is directly effected by the frequency utilised.

Figure : Illustration showing the broad range of frequencies within the electromagnetic spectrum that RFID systems can utilise

RFID transmission frequencies are roughly classified into the three ranges: 

• LF (low frequency, 30-300 kHz),  

• HF (high frequency)/RF radio frequency (3-30 MHz) 

• UHF (ultra high frequency, 300 MHz-3 GHz)/microwave (>3 GHz).

However, the specific absorption rate (i.e. how much energy is lost as it passes through an object) of non-conductive substances (and water) is smaller by a factor of 100 000 at 100 kHz than it is at 1 GHz, so practically no energy is lost. The result of this is that systems operating at these frequencies will typically have a greater range. That said, lower frequency systems are noted for their improved object penetration over higher frequency ones.

RFID systems are also classified by range into: 

• Close-coupling (0-1 cm),  

• Remote-coupling (0-1 m), 

• Long-range (>1 m) systems.

These ranges represent the theoretical maximum that could be achieved, and although clearly an important factor, the achievable range of communication between RFID tag and reader is dependent not only on the frequency utilised, but also a host of other factors. This can be issues such as the positional accuracy of the transponder, the minimum distance between several transponders in practical operation and the speed of the transponder in the interrogation zone of the reader (Finkenzeller, 2003).