THE ANATOMY OF RFID
To cut the story short, RFID is a wireless system basically made of three basic components, tags, readers and antennas, which communicate over the air at a certain frequency, exactly like radio stations.
RFID tags are “smart objects“, which can store a set of information, from a simple and unique ID number (so called EPC – electronic product code) to significant volumes of datas (just to be crystal clear, we are talking about thousands of bytes not GBs).
Tags use radio waves to communicate their identity and other information they carry around, to nearby readers, with no need of physical contact.
They can be passive or active.
- Passive RFID tags are powered and activated by the reader in order to backscatter the information contained in their memory. They do not have a battery and absorb the energy they need from the reader’s antenna. These are the most common used tags in various industries and sectors as they are more flexible, cheaper, smaller, easier to embed. They also have a wider option range and a longer duration.
- Active RFID tags are powered by batteries. They have a wider reading range, but are more expensive, bigger volume, short duration and require higher efforts for embedding.
Note: the choice between passive or active tags depends on the application and other field variables we will examine later on.
An RFID reader is like a radio (no jokes), just like the one you have in your car, except for the fact id does not play classic music but “talks” with the tags.
It is a communication device that emits radio waves, receives signals back from the RFID tags (this is why they are also called “trasponders”), reads the information contained in the chip (in bulk and from a variable distance) and send them out to WMS or ERP system (to be precise there is actually a previous intermediate step at middleware level, but let’s forget this geek’s detail at least for now).
Readers can be mobile or stationary.
Both tags and readers have their own antenna, as they are both radio devices.
The antennas are the intermediaries between tags and readers to transmit the radio frequency signal, receive the information contained in the RFID tag, and then transmit it to the company’s management system (WMS or ERP).
Simply said, antennas are the “king of the hill“, without them no reader would be able to broadcast.
You can find different types of antennas in the market, which come in a variety of shapes and sizes: linear or circular, indoor or outdoor, 13,56 MHz or 860-960 MHz, incorporated into the RFID reader or external. This is all you need to know for now, unless you aspire to become an “antenna guru” :)
Here we come to the most exciting topic :)
Both the tags and the readers operate over a certain frequency, exactly lika a radio station.
The most common are:
- Low frequency, or LF, (125 – 134 kHz)
- High frequency, or HF, (13.56 MHz)
- Ultra-high frequency, or UHF, (860-960 MHz)
Without going too deep, all you need to know for now, is that the frequency choice depends on the application and the country where you are deploying your network.
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