Powerful RFID technology from Phoenix Contact.
RFID stands for Radio Frequency Identification and means that objects can be identified without physical or visual contact. An RFID system consists of a transponder and a read or read/write unit. A range of different RFID systems are available on the market. However, all share three common properties:
With this in mind, there are certain basic functions that every RFID system must fulfil. Depending on the area of application, the RFID systems can offer a wide range of additional functions.
RFID system types
RFID operating principle
The transport medium for exchanging data between the transponder and the read or read/write unit is radio waves. Different frequency ranges are used for RFID systems.
Low frequency (NF) | High frequency (HF) | Ultrahigh frequency (UHF) | Microwave frequency (SHF) | |
---|---|---|---|---|
Frequency | 30 - 500 kHz | 13.56 MHz | 850 or 950 MHz | 2.45 or 5.8 GHz |
Range | Up to 1.2 m | 0.01 - 0.3 m | 2.5 m | Up to 300 m |
Reading speed | Slow | Depending on ISO standard | Fast | Very fast (active transponder) |
Typical transponder | Smart label, Transponder in plastic sleeves, Card transponder | Smart label | Smart label | Large-format transponder |
There are two basic types of RFID transponders: Active transponders have their own energy supply. They are only activated if a read or read/write unit sends commands within the transponder range.
Passive transponders are supplied with energy from the read or read/write unit. This energy supply can come from an inductive coupling or through the backscatter method. In inductive coupling, the electromagnetic field of the read or read/write unit induces a current at the transponder antenna. This current is rectified in the second step.
Systems with high ranges often use the backscatter method. For this, both the transponder as well as the read or read/write unit require a dipole antenna with resonance behavior for the respective frequency of the RFID system. If the antenna on the read or read/write unit emits transmission power, this is available on the transponder antenna as high-frequency current. The transponder uses it by means of rectification for the power supply.
Transponders for industrial identification also exhibit a range of different designs, e.g.:
Coupling elements such as coils or antennas on transponders and the read or read/write unit facilitate data transmission between the two components.
The read or read/write unit creates a high-frequency, electromagnetic alternating field. If a transponder is located within this field, communication can take place. The induction generates a current in the transponder coil. The transponder electronics generate an additional signal from this, which is sent back as a response to the read or read/write unit.
For data transmission between the transponder and read or read/write unit, there are different operating modes.
Process | Power transmission | Data transmission |
---|---|---|
Full-duplex process (FDX) | Continuous | Simultaneous data up and downlink |
Half-duplex process (HDX) | Continuous | Sequential data up and downlink |
Sequential process | Sequential | Sequential data up and downlink |
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