The previous article has already introduced what is rfid tag. Today we will talk about the features of the LF RFID tag.

For an RFID system, its frequency band concept refers to the frequency range of the tag signal that the reader sends, receives, and reads through the antenna. From the application concept, the operating frequency of the radio frequency tag is also the operating frequency of the radio frequency identification system, which directly determines various aspects of the system application. In an RFID system, similar to how a radio must be tuned to different frequencies to hear different channels, RFID tags and readers have to be tuned to the same frequency in order to communicate.

Definition

RFID comes in two flavors, Active RFID and Passive RFID. Within passive RFID, there are three main tag / reader technologies on the market today, named after their respective frequency bands: low-frequency , high-frequency , and ultra-high-frequency . The Low Frequency (LF) band covers frequencies from 30 KHz to 300 KHz. Typically LF RFID systems operate at 125 KHz, although there are some that operate at 134 KHz. Within each passive RFID frequency band, there are a handful of ISO standards that need to be followed in order to facilitate reader to tag communication. the major standards for LF passive RFID frequency band is ISO 14223 and ISO/IEC 18000-2.

Technical Foundation

The technical basis of RFID tags is divided into inductive coupling and electromagnetic coupling.The LF tags are based on inductive coupling technology which means that the RFID reader induces a current in the RFID tag which then powers the RFID tag and sends out some basic identification information to the RFID reader. LF tags are usually passive and do not require a power source or battery.Low Frequency RFID tags have a long wavelength and can penetrate thin metal surfaces (HF and UHF tags can usually not be used with metallic substances). They can also operate in environments with high water content – so fruits, liquids and even animal tagging.

Reading Range

Since LF RFID tags are based on inductive coupling technology their read range is limited to a few centimeters or inches. This limited range can be used in a number of applications to provide an increased level of security i.e the RFID system will only work when the tag is close to the reader. This can be used when wanting to exchange sensitive information or for car ignition, where the RFID tag can be embedded in the key and read by a reader that is in the car. The system will only work when you are close to the car. The difference in the operating frequency imposes a difference in the reader construction. For example, the antenna for 125khz reader is made with copper wires, due to the relatively low frequency, but the antenna for 13,56mhz can be made directly on the PCB with traces.

Applications

LF RFID systems are used most often for animal tracking applications (e.g. pet tagging and livestock identification), LF tags are ideal for animal tracking applications because they are easily read through the animal’s body (containing water).
LF RFID tag is also ideal for the following applications:
access control
asset tracking
laundry
automotive control
as vehicle immobilizers
healthcare

Advantages:

1. The LF RFID tag chip generally adopts a common CMOS process and has the characteristics of power saving and low cost;
2. LF RFID tag operating frequency is not subject to radio frequency control, and is affected by temperature, humidity, and obstacles. It can be used with metallic substances;

Disadvantage:

1.The reading distance is short, generally less than 8cm;
2.Slow data transfer;
3.The amount of stored data is small;
4.Poor flexibility, not easy to be identified;
5.Poor security and confidentiality, easy to be cracked.

 

LF RFID Tag Properties
Tag Type Passive
Technology Inductive Coupling
Frequency 125 KHz / 134 KHz
Read Rage Short (few cm to Inches)
Read Speed Slow
Works with Metal Yes
Works with Liquids Yes
Cost Low

 

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