RFID- also known as Radio Frequency Identification is automatic recognition technology that uses wireless communication. Generally, a system or a part that uses an IC tag to identify or control various items via wireless communication is called RFID. In this article, we will give a description of the features of RFID and explain the principle of wireless communication in order to provide basic knowledge concerning RFID to you.

RFID Radio frequency identification is wireless technology that uses electromagnetic or electrostatic coupling in the radio frequency portion of the electromagnetic spectrum to uniquely identify an object, animal or person. RFID presents more popularly than you could imagine, it is applied in surrounding appliances and enters profoundly in your daily life, for example contactless payment. RFID systems are used in many fields, most commonly used for livestock tracking, inventory management, supply chain logistics and vehicle tracking. Moreover, RFID systems are prevalent in industries such as healthcare manufacturing, retail business and even home use.

If you have heard about the barcode technology, you may see that RFID has a similarity to it. However, there are still differences between two of them as RFID can scan from a few inches to a few feet away, and do not require a direct line of sight to be read, they can be updated in real time and they require a power source.

Next, let’s look at its feature

As I have mentioned above, RFID does not require a direct line of sight, which means data can be read at long distances up to several meters.

RFID is applied widely in many fields and helps with optimizing the working process as: helps data in multiple tags can be read at once, helps reduce the time required to carry out stocktaking, etc.

Data can also be read even being covered (by a box or by dirt on tags). Unlike barcode, which can not be read when the surface is damaged

Compared to barcode, RFID contains and exchanges a much larger amount of data.

Now you may have a general picture of RFID, what it is applied for and what it can do.

Then take a look at the inner parts.

Every RFID system consists of three components:

a scanning antenna
a transceiver
a transponder

You can understand that the scanning antenna and transceiver play the role of an RFID reader or interrogator.

The RFID reader is a network-connected device that can be portable or permanently attached. To be more clear, RFID readers have many sizes and shapes. It transmits signals that activate the tag via radio wave. Then, a wave sent from the activated tag back to the antenna is translated into data.

The RFID tag’s built-in transponder. The type of tag, reader, RFID frequency, and interference from other RFID tags and readers are some of the factors that affect the read range of RFID tags. Active RFID tags have a longer read range than passive RFID tags due to the stronger power source.

The RFID reader

This RFID reader mainly consists of three components.

So the first component of the RFID reader is the RF signal generator. The radio waves are generated by this signal generator then are transmitted by antenna. Also to receive the feedback signal which is coming from the tag, the RFID reader also has a receiver or signal detector. And to process the information which is being sent by the RFID tag, this RFID reader also has a microcontroller. Or many times this RFID reader is directly connected to the computer.

RFID tags

RFID tags are made up of an integrated circuit (IC), an antenna, and a substrate. Inside an RFID tag, a segment encodes identifying information called the RFID inlay.

There are two main types of RFID tags:

Active RFID. An active RFID tag has its own power source, often a battery.
Passive RFID. A passive RFID tag receives its power from the reading antenna, whose electromagnetic wave induces a current in the RFID tag’s antenna.

There are also semi-passive RFID tags, meaning a battery runs the circuitry while communication is powered by the RFID reader.

Most of the tags, which are being used today are passive tags. Because these passive tags are quite cheaper compared to the active ones, as well as, as they do not require any power source, so they are quite compact. These passive tags are also coming in many forms.

Low-power, embedded non-volatile memory plays an important role in every RFID system. RFID tags typically hold less than 2,000 KB of data, including a unique identifier/serial number. Tags can be read-only or read-write, where data can be added by the reader or existing data overwritten.

Inside this RFID tag.

So, the first basic component that you see inside an RFID tag is a transponder. which receives the radio waves which are coming from the reader and sends the feedback signal back to the reader. As the passive tags do not have their own supply so they rely on the radio waves which are coming from the reader. they used to get the energy from the radio waves which are coming from the reader. So, using this rectifier circuit the energy that is coming from the radio waves is stored across the capacitor. And this energy is used as a supply for the controller as well as the memory element inside is RFID tag.

What are the types of RFID systems?

There are three main types of RFID systems: low frequency (LF), high frequency (HF) and ultra-high frequency (UHF). Microwave RFID is also available. Frequencies vary greatly by country and region.

Low-frequency RFID systems.
High-frequency RFID systems
UHF RFID systems.

So this frequency range or frequency of operation varies from country to country. But the majority of the countries used to follow this frequency for the operation for the RFID tags. So, as these low frequency signals can travel a very short distance, the range of RFID tags which are using this low frequency range is up to 10 cm. So these high frequency radio waves can travel up to 1 m. While the Ultra High Frequency radio waves can travel much longer. So the RFID tags which are using this Ultra high frequency can travel up to 10 to 15 Meters. So now, let us see the working principle for this RFID tag. Now this working principle also depends upon the frequency of operation. So, for the low frequency and the high frequency operation the working principle is based on the inductive coupling. While in case of Ultra high frequency RFID tags,the working principle is based on electromagnetic coupling.

Working principle

About the working principle for this low frequency and high frequency RFID tags.

So, as I mentioned above, this RFID reader continuously sends radio waves with a particular frequency. This radio wave which is being sent by this RFID reader serves 3 purposes. First it induces enough power into the passive tag. Second, it provides the synchronization clock for the passive tag. Third, it acts as a career for the data which is coming back from the RFID tag.

In case of a low frequency and high frequency operation as a RFID reader and tag are very close to each other, their working principle is based on the inductive coupling. The field which is generated by this RFID reader used to be coupled with the antenna of a RFID tag. And because of this mutual coupling, the voltage will get induced across the coil of the RFID tag. Now some portion of this voltage is getting rectified and used as a power supply for the controller as well as the memory elements. As the RFID reader is sending radio waves of a particular frequency, so the voltage that is induced across the coil is also of a particular frequency. This induced voltage is also used to derive the synchronization clock for the controller. So now suppose if we connect a load of the coil, then current will start flowing through this load. And if we change the impedance of this load then the current that is flowing through this load will also get changed. So, this switching of current or rate of change of current also generates a voltage in a RFID reader. So, in this way, in a low frequency and high frequency RFID tag, using this load modulation technique the data is being sent back to the RFID reader.

About the working principle of the Ultra high frequency

Let’s see the working principle for the Ultra high frequency. As the distance between the reader and the tag is up to a few meters, the coupling between the reader and the coil will be the Fire field coupling. This RFID reader continuously sends the radio waves of a particular frequency towards the tag, and in response, this tag is sending a weak signal to the RFID reader. Now this weak signal which is being sent back to the RFID reader is known as the backscattered signal. And the intensity of this back scattered signal depends upon the load matching across the coil. So if the load is matched exactly, then the intensity of the back scattered signal will be more. So, in this way, by changing the condition of a load we can change the intensity of this backscattered signal. Now in case of a powerful coupling, as the distance between the RFID reader and Tag is a few meters, the initial signal which is being sent by The Reader should be strong, so that the back scattered signal can be retrieved by this RFID reader. So this is how in a case of a far field coupling, the signal is sent back to the RFID reader using this back scattered modulation technique.

So that’s all the information we have collected about RFID and we hope that this information can please your requirement of RFID Technology knowledge.

What is RFID? Explain in detail how RFID works and contributes in life?