Applications of RFID

1. Employee Identification and Access Control
2. Airline baggage Identification
3. Wafer Identification during manufacturing process
4. Livestock Identification
5. Parts Identification
6. Identification and Tracking of Vehicles
7. Identification of  widgets through manufacturing process
8. Supply Chain Automation
9. Asset Tracking, and others.

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).