How RFID Works-Everything That You Need To Know!

RFID Chip, Equivalent to the size of Rice Grain
RFID Chip, Equivalent to the size of Rice Grain
RFID is an acronym for "radio-frequency identification" and refers to a technology where digital data encoded in RFID tags or smart labels are captured by a reader via radio waves. RFID is similar to barcoding in that data from a tag or label. RFID, however, has several advantages over systems that use barcode asset tracking software. The most notable is that RFID tag data can be read outside the line-of-sight, whereas barcodes must be aligned with an optical scanner. 
RFID- Reading Network
RFID- Reading Network
 A Radio-Frequency Identification system consists of 3 parts:
  • 1. A scanning antenna
  • 2. A transceiver with a decoder to interpret the data
  • 3. A transponder - the RFID tag - that has been programmed with information. 
An absolutely key part of the technology; RFID tags do not need to contain batteries, and can therefore remain usable for very long periods of time (maybe decades).

The Radio Frequency radiation does 2 things:
  • 1. It provides a means of communicating with the transponder (the RFID tag).
  • 2. It provides the RFID tag with the energy to communicate (in the case of passive RFID tags). 

RFID Tags Are Of 2 Types:-

Active Tag :

**An active tag when, it is attached with a battery or power source for the tag's circuitry & antenna. Some of the active tags available in the market contain replaceable batteries;  & others come in sealed units.

Major advantages of an active RFID tags are:
  • 1. It can be interpreted at distances of 100+ feet, thus greatly improve the mobility of the device.
  • 2. It may have other sensors attached.

The problems and disadvantages of an active RFID tag are:
  • 1. The tag cannot function without battery power, which limits the lifetime of the tag.
  • 2. The tag is typically more expensive.
  • 3. The tag is physically larger, which may limit applications.
  • 4. The long-term maintenance costs for an active RFID tag can be greater than those of a passive tag if the batteries are replaced.

Active RFID tags may have the following features:
  • 1. Longest of the range of communication of any other tag in the market.
  • 2. To perform independent monitoring and control.
  • 3. The capability of initiating communications.
  • 4. To perform diagnostics.
  • 5. To attain highest data transmission bandwidth.

Passive Tag:

A passive tag does not contain a battery. When radio waves from the reader are encountered by a passive RFID tag, the coiled antenna in the tag forms a magnetic field. The tag obtains power from it, energizing the circuits in the tag. The tag then sends the information written in the tag's memory. 

 The advantages of a passive tag are:
  • 1. The tag functions without a battery & have a useful life of 20+ years.
  • 2. Much less expensive to manufacture
  • 3. The tag is much smaller (some tags are the size of a grain of rice).

The major disadvantages are:
  • 1. The tag can be interpreted only at a very short distances, typically a few feet at most.
  • 2. It might not be possible to include sensors that use power to operate.
  • 3. The tag remains readable for a very long time, even when the product has been sold.


**When an RFID tag passes through the field of the scanning antenna, it detects the activation signal from the antenna. That "wakes up" the RFID chip, and it transmits the information on its microchip to be picked up by the scanning antenna.

An EPC RFID tag used by Wal-Mart.
An EPC RFID tag used by Wal-Mart.

RFID tags can be read in a wide variety of circumstances, where barcodes or other optically read technologies are useless.
  • 1. The tag need not be on the surface of the object (no subject to wear)
  • 2. The read time is typically less than 100 milliseconds
  • 3. Large numbers of tags can be read at once rather than item by item. 

RFID uses:

  • # Animal tracking tags, whales, dogs, cats, pets, etc
  • # To identify trees or wooden items.
  • # The anti-theft hard plastic tags attached to merchandise in stores/shopping malls are also RFID tags.
  • # Heavy-duty 120 by 100 by 50 millimeter rectangular transponders are used to track shipping containers, or heavy machinery, trucks, and railroad cars.
  • # Inventory management
  • # Asset tracking
  • # Personnel tracking
  • # Controlling access to restricted areas
  • # ID badging
  • # Supply chain management
  • # Counterfeit prevention (e.g., in the pharmaceutical industry)



RFID used inside a living body:

RFID devices that are intended to be implanted inside a living body (like an animal or human being) have special requirements. They need to be encased in a special kind of casing that will not irritate or react with the living tissues that they are inserted into. The casing must also be transparent to the scanning radio-frequency beam that activates the chip. Some RFID vendors have created biocompatible glass for use in these applications.

Note: The amount of information that the tag stores can vary. Passive tags, only store about 1024 bytes of information, or 1 kB. That will contain all the information like
full name, address, phone number, birthday, bank account number, place of birth and mother’s & father's name in only 130 bytes of information in plain text.

RFID Reader
RFID Reader

Drawbacks With RFID:

No particular RFID Standard:  There is no Global standards of RFID they are still being worked on. Its notable that some RFID devices never ever meant to leave their network (especially in case inventory control). This causes various problems.

RFID Network Can Easily Be Jammed: Since RFID systems use electromagnetic waves (like WiFi networks or cellphones), they are relatively easy to get jammed using energy at the right frequency, which is of that of operating frequency of RFID tag. Although this would only be an inconvenient factor for consumers in stores (due to longer waiting time at checkout), & more over it could be disastrous in othersituations where RFID is used intensively, like  in military or in the hospitals.

RFID Reader Collision:

Reader collision occurs when the signals from two or more readers overlap. The tag is unable to respond to simultaneous queries. Systems must be carefully set up to avoid this problem; many systems use an anti-collision protocol.

RFID Tag Collision:

Tag collision occurs when many tags are present in a small area; but since the read time is very fast, it is easier for users to develop systems that ensure that tags respond one at a time. 


Difficulty of RFID tags to get removed:

RFID tags are difficult for users to remove; some are very-very tiny(less than a a millimeter square) other types of RFID IDs may be hidden or embedded inside a product where consumers can't have a look of them. New technologies allow RFID tags to be "printed" right on a product and may not be removable at all.

RFID tags can be sensed from a greater distance with an antenna of high gain:

An antenna of high gain it can be used to read the tags from much far away distance, it can lead to certain privacy issues, thereby it may be not used in certain area..