Active RFID vs. Passive RFID: which differences?

Published on 06 avr. 2019 In: Techno

  • Reading time08 min.
  • LevelBeginner

You might have heard of RFID (Radio Frequency Identification), but do you really know what it is about, and which kinds of RFID are being used? Radio Frequency Identification is useful in many different sectors and applies to various processes such as inventory management, access control or industrial equipment automated identification.

Active RFID vs. Passive RFID: which differences?

Radio Frequency Identification (RFID) is frequently used on a daily basis, without us even being aware of it, in many various fields of activity. It allows data transmission, storage and remote data recovery by means of radio waves. RFID is often used for product identification and automatic information gathering on specific items, with no need for any physical connection, unlike other technologies such as gencode for example. In most cases, this might be applied in two different ways, called active RFID or passive RFID.

 

RFID basics

 

RFID basic devices consist of several components. Among them, the tag, also called "radio tag", includes an electronic chip for data identification and storage, an antenna for communication purposes, as well as a reader or interviewer for wave transmission and reception. A computer and software are also required for data backup and analysis. Depending on the radio tag that is being used, you may need a battery or no battery at all (passive tags), a battery may be required only for wave transmission (semi-passive tags) or to power the tag and wave transmission (active tags).

 

RFID tags

The RFID tag is a critical electronic identification device. It usually consists of two main components: an antenna receiving the waves and an electronic circuit designed for information processing and storage. In other words, it contains an identifier and associated data on a chip, which is itself connected to the antenna. The tag transmits data to a reader by means of radio waves. Very popular in the RFID industry, tags are very useful for meeting traceability requirements, for example, since they do not necessarily need to be visible in order to be detected and, thus, to be read.

 

Reader

The reader is an electronic device used for transmission and reception of electromagnetic waves. It is able to detect and recognize the tag credentials through the ID provided by the chip manufacturer. It may also use a decoder in order to read the information carried by the incident wave.

 

RFID antenna

The RFID antenna is designed for collecting and broadcasting electromagnetic waves. The transmission frequency depends on the antenna type, its wavelength and the selected chip frequency. In accordance with the specific application, the antenna should be as low-cost, non-invasive and as eco-friendly as possible. In order to optimize energy flow, the antenna impedance must be equivalent to the electronic chip impedance provided in the tag. In most cases, this impedance value is of 50?.

 

Computer

The computer and software allow to save the information collected by the reader. In some cases, they also may trigger the reader.

 

RFID basic functionalities

 

Active RFID

 

The first concept is about active RFID. In this case, an on-board power source is used to for operating tags. It may be a battery or a cell, for example, enabling both tag performance and data transmission.

Active RFID applies to several industries, such as construction, public works and security, as well as home automation. Active tags are mainly used for monitoring physical parameters (such as temperature, humidity, movement). This applies in particular to cold chain control in refrigerated trucks. They also make it possible to identify and track people for on-site safety. Lastly, they may also be used for access control or automatic goods identification.

STRENGHTS

  • Main strength: high distance coverage
  • Increased information storage capacity compared to passive tags
  • Tags providing various additional functions
  • Fast data transfer rate
  • Possibility to read a large number of labels simultaneously

WEAKNESSES

  • Tags are costly and have a limited lifespan
  • These tags are rather intrusive, given their medium size, which makes them visible

coverage / range

Active tags have a very long coverage range, exceeding 500 m. Other technologies (further information in other articles of this blog) make it possible to extend this distance to up to one kilometer.

 

Passive RFID

 

The second case concerns passive RFID. Unlike active tags, passive tags do not include any embedded power source. As an alternative, the reader wave is used as a power source for the chip, in order to modulate the signal and to broadcast the signal back to the reader by back scattering.

 

STRENGHTS

  • It is low cost.
  • It is time saving.
  • It uses flexible materials. In fact, tags may sometimes be made of paper or textile, making them more environmentally friendly (provided that the metal ink used in the antenna also is eco-friendly).
  • It includes significant highlights such as their small size, lightweight and long lifespan.

STRENGHTS

  • This device may read only very few labels simultaneously.
  • Their decreased range and reliability - compared to those provided by active tags - make them less reliable and more fragile.

coverage / range

Passive tags have a 3-level range.

  • We are talking about short distance with a Low Frequency, when referring to a contact located only a few centimeters away.  
  • The average distance represents a range held between a few centimeters up to 1m. This is known as High Frequency. For instance, NFC has a reading distance of 10 cm in most cases.
  • Lastly, the maximum distance extends up to 15m and relies on the Ultra High Frequency technology.

 

To go even further...

 

You may also find a third type of RFID, called semi-passive. Although less famous and therefore less used, this device incorporates some active RFID features (such as a battery placed on the tag, to provide power only at this time) and passive RFID features (for transmission purposes). These tags have a longer lifespan than an active tag and are cheaper. However, they remain more expensive than the passive ones.









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