RFID tags are being used in a vast variety of industries in modern times, be it for tracking, collecting information, inventory, research, etc. One integral part of this technology is the receiving antennas. Many types of RFID antennas are used to activate RFID tags & capture their signals. Today we will discuss one such type of antenna, called Far-Field antennas.
So, let’s start with learning what exactly far-field technology is.
What is a Far-Field Antenna?
Before we talk about what far-field antennas are, we need to first discuss how RFID antennas work & the meaning of far-field. RFID antennas work by creating an electromagnetic field around them. Then, depending on the type of the RFID tag – Active or passive, there are two ways they communicate.
Active Tags broadcast signals using their power that can be picked up by the antenna. For passive tags, once they enter the electromagnetic field of the antenna, they reflect it to communicate.
We can divide the electromagnetic field that an antenna creates around itself into two parts – Near Field & Far Field. Near-Field refers to the circular area inside an electromagnetic field, whose radius is equal to one wavelength of the frequency of the signal. On the other hand, the field area outside of that is called the Far-Field area.
How Do Far-Field Antennas Work?
Far-Field antennas communicate with RFID tags, through a phenomenon called Capacitive Electromagnetic Coupling. This is a means of transferring electrical energy from one circuit to another, using radio waves. Far-Field antennas broadcast radio signals, and when these signals hit an RFID tag, they energize them using coupling. The tag then uses this energy & sends back a signal which is received by the antenna.
Using this technique, far-field antennas can have a communication range of up to 9 meters. There are several different types of far-field antennas to select from.
How to Best Use Far-Field RFID Antennas?
As the name suggests, the best application of a far-field antenna comes into focus in situations where the tag & the antenna are far apart. Primarily, these antennas are used in warehouses, supply lines, retail stores, etc.
In warehouses, far-field antennas are used for the purpose of pallet tracking. In Supply lines, you can use these antennas to track the real-time movement of products. Retail stores have multiple uses for far-field antennas, they are used for real-time tracking and inventory updating & management.
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