RFID Standards:

Several RFID standards are defined already, and several are under consideration.

1. Identification cards - contactless integrated circuit cards
ISO 10536 (ISO SC17/WG8)	Close coupled cards
ISO 14443 (ISO SC17/WG8)	proximity cards
ISO 15693 (ISO SC17/WG8)	vicinity cards
ISO 10373 (SC17/WG1/8)	Identification cards - Test Methods
2. Item Management
ISO 10374 (ISO TC 104)	Freight containers - Automatic identification
ISO 15960 (SC31 WG2/4)	RFID for Item Management; - Transaction Message Profiles
ISO 18001 (SC31 WG4)	Information technology - RFID for Item Management - Application Requirements Profiles
3. Animal ID
ISO 11784 (ISO TC 23/WG19)	Radio-frequency identification of animals - code structure
ISO 11785 (ISO TC 23/WG19)	Radio-frequency identification of animals - technical concept
4. Radio Regulation
CEPT	Road Transport Information Systems
5. Others
UPU	contactless stamps

RFID Frequencies:

There are several frequencies that are used for RFID. These include LF, HF, UHF, and Microwave frequencies. The exact frequencies may vary depending on the country where it is used.

Frequency Range	Description	Typical Applications
<135khz span="span">	Low Frequency, Inductive coupling	Access Control & Security Widgets identification through manufacturing processes Ranch animal identification OEM applications
13.56 MHz	High Frequency, Inductive coupling	Access Control Library books Laundry identification OEM applications
868 to 870 MHz 902 to 928 MHz	Ultra High Frequencies (UHF), Backscatter coupling	Supply chain tracking
2.400 to 2.483 GHz	SHF, Backscatter coupling	Asset tracking Highway toll tags Vehicle tracking

a. RFID Building Blocks:

Tags: A tag is the data carrier and normally contains the ID number, and unique EPC code programmed into the Tag
Tag Antenna: The tag antenna is connected to the chip in tag. It could be wire or printed using conductive ink.
Reader Antenna: It is a coil included in plastic or similar case, and normally measures 12 -18 inches square
Reader: A reader captures the data provided by the tag within the detectable area of the Reader. There can be one or more tags within the capture area. A reader is typically capable of reading multiple tags simultaneously.
Savant: This is normally a middleware that interacts with the readers, and communicate with External databases.

b. RFID Block Schematic:

A simplified block schematic of an RFID tag (also called transponder) is shown in the diagram below. Various components of the tag are as shown. Normally, the antenna is external to the tag chip, and large in size.

The operation of the RFID tag is described below:

Handshaking with the Reader (interrogator):

• The reader continuously emits RF carrier signals, and keeps observing the received RF signals for data.
• The presence of a tag (for our discussion, we consider only passive tag) modulates the rf field, and the same is detected by the reader.
• The passive tag absorbs a small portion of the energy emitted by the reader, and starts sending modulated information when sufficient energy is acquired from the rf field generated by the reader. Note that the data modulation (modulation for 0s and 1s) is accomplished by either direct modulation or FSK or Phase modulation.
• The reader demodulates the signals received from the tag antenna, and decodes the same for further processing.

c. Backscatter Modulation:

Backscatter is one of the most widely used modulation schemes for modulating data on to rf carrier. In this method of modulation, the tag coil (load) is shunted depending on the bit sequence received. This in turn modulates the rf carrier amplitude as shown in the diagram below. The reader detects the changes in the modulated carrier and recovers the data.

The above diagram provides a simplified modulated carrier signals from the RFID tag. As seen in the diagram, the encoded binary digits modulate rf carrier. A 1 is represented with high carrier level, and a 0 is represented by a low carrier level (tag coil shunted). The reader demodulates the signals to recover the data, and note that this data is still encoded. The reader decodes the data using suitable decoder, and forwards it for further processing to a computer (or any backend server).

Introduction to Radio Frequency Identification

a. What is RFID

RFID, short for Rradio Frequency IDentification, is a technology that enables identification of a tag (that is normally attached with an entity) by using electromagnetic waves. The function served by RFID is similar to bar code identification, but line of sight signals are not required for operation of RFID. Important components of an RFID system are:

• An RFID reader (also called transceiver) with an antenna and a transceiver,
• A transponder (Also called a tag) that includes an antenna and a chip)

b. Compare RFID with Bar Code Technology

Given below are the brief differences between the Barcode technology and RFID:

Parameter	Bar Code	RFID
Frequencies used for tag reading	Optical frequencies	Radio frequencies
Type of communication	Line of sight communication	Non-Line of sight communication
Data Volume	Physical limitation exists. It is very difficult to read a very long barcode.	Can carry relatively large volume of data.
Range of data readability	Very limited range, less than a feet or two.	Can be read up to several feet.
Cost	Cheap	Expensive, but likely to cost less as more industries adopt the technology.

c. Benefits of RFID

The following are the benefits of RFID Systems:

• Non-line of sight identification of tags.
• Unattended operations are possible, minimizing human errors and high cost.
• Ability to identify moving elements that have tags embedded.
• Larger area of coverage. Up to several feet.
• Can be used in diverse environments, including live stock, military, and scientific areas.
• RFID can be used in addition to Bar Code. These two technologies can be complementing each other.
• Automatic integration with back end software solutions provide end to end integration of data in real time.

d. Disadvantages of RFID:

• Expensive compared with Bar code
• Bulkier, due to embedding of electronic components in the tag. However, with advanced techniques, it is possible to reduce the size, and weight of the tags to a large extent.
• Prone to physical/electrical damage due to environmental conditions. For example, tags that are subjected to space exploration may encounter extreme temperatures. The tags required to be designed for a given application, and may be costly when designed for use under extreme environmental conditions.

·         Active and Passive RFID Tags:

·         There are primarily two types of RFID tags. One is active and the other is passive. An active tag is powered using internal battery, where a passive tag gets energized using a the power from a tag reader. A passive RFID tag will not have a battery or any kind of power source by itself. It extracts the required energy from a reader. Hence, a passive RFID tag reader must be able to emit stronger electromagnetic signals, and in return, identify very weak signals from the passive RFID tag.

·         Given below are the primary differences between a Passive and Active RFID tags:

·          

	Passive RFID	Active RFID
Power Source	External (Reader provided)	Internal (Battery)
Tag Readability	Only within the area covered by the reader, typically up to 3 meters.	Can provide signals over an extended range, typically up to 100 meters..
Energization	A passive tag is energized only when there is a reader present.	An active tag is always energized.
Magnetic Field Strength	High, since the tag draws power from the electromagnetic field provided by the reader.	Low, since the tag emits signals using internal battery source.
Shelf Life	Very high, ideally does not expire over a life time.	Limited to about 5 years, the life of a battery.
Data storage	Limited data storage, typically 128 bytes.	Can store larger amounts of data.
Cost	Cheap	Expensive
Size	Smaller	Slightly bulky (due to battery)