SHORT ARTICLE ABOUT RFID (Radio Frequency Identification)

RFID (radio frequency identification) is a form of wireless communication that incorporates the use of electromagnetic or electrostatic coupling in the radio frequency portion of the electromagnetic spectrum to uniquely identify an object, animal or person. Use cases for RFID technology include healthcare, manufacturing, inventory management, shipping, retail sales and home use.

RFID and barcode technology are used in similar ways to track inventory, but three important differences make each one a better choice in certain situations:

• RFID tags do not require a direct line of sight to be read.


• Data stored in an RFID tag can be updated in real-time. In contrast, bar code data is read-only and cannot be changed.


• RFID tags require a power source. In contrast, bar codes only require the technology reading the bar code to have a power source.

How RFID Works

Radio Frequency Identification (RFID) is the wireless non-contact use of radio frequency waves to transfer data. Tagging items with RFID tags allows users to automatically and uniquely identify and track inventory and assets. RFID takes auto-ID technology to the next level by allowing tags to be read without line of sight and, depending on the type of RFID, having a read range between a few centimeters to over 20+ meters.

RFID has come a long way from its first application of identifying airplanes as friend or foe in World War II. Not only does the technology continue to improve year over year, but the cost of implementing and using an RFID system continues to decrease, making RFID more cost-effective and efficient.

Types of RFID Tags

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

There are two main types of RFID tags: active RFID and passive RFID. An active RFID tag has its own power source, often a battery. A passive RFID tag, on the other hand, does not require batteries; rather it 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.

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.

The read range for RFID tags varies based on factors including type of tag, type of reader, RFID frequency, and interference in the surrounding environment or from other RFID tags and readers. Generally speaking, active RFID tags have a longer read range than passive RFID tags due to the stronger power source.

RFID Frequencies

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 range from 30 KHz to 500 KHz, though the typical frequency is 125 KHz. LF RFID has short transmission ranges, generally anywhere from a few inches to less than six feet.


• High-frequency RFID systems range from 3 MHz to 30 MHz, with the typical HF frequency being 13.56 MHz. The standard range is anywhere from a few inches to several feet.


• UHF RFID systems range from 300 MHz to 960 MHz, with the typical frequency of 433 MHz and can generally be read from 25-plus feet away.


• Microwave RFID systems run at 2.45 GHz and can be read from more than 30-plus feet away.

The frequency used will depend on the RFID application, with actual obtained distances sometimes varying considerably from what might be expected. For example, when the U.S. State Department announced it was to issue electronic passports enabled with an RFID chip, it said the chips would only be able to be read from approximately four inches away. However, the State Department was soon confronted with evidence that RFID readers could skim the information from the RFID tags from much farther than 4 inches, some claiming upward of 33 feet away, proving the difference between advertised and actual range can vary immensely.

If read longer ranges are needed, using particular tags with additional power can boost read ranges to 300-plus feet.

RFID vs Barcode

Using RFID as an alternative for barcodes is increasing in use. Among its benefits, RFID can identify individual objects, animals or people without direct line of sight, can identify many items  often a thousand or more simultaneously, and can scan items anywhere from inches to feet away depending on the type of tag and RFID reader. Read time for RFID tags is typically less than 100 milliseconds.

Barcodes, on the other hand, require direct line of sight and closer proximity than an RFID tag. They also take longer to read, generally ½ second or more per tag. Because barcodes represent a product type versus an individual object represented by an RFID tag, additional information cannot be gleaned from them. In addition, barcodes are not read-write, and because they are printed on the outside of the object are limited in terms of reuse thanks to wear and tear. RFID tags are more rugged and better protected, often in a plastic cover. However, RFID tags cost more than a printed barcode.

RFID vs NFC

Near-field communication (NFC) allows data to be exchanged between devices by using short-range, high-frequency wireless communication technology. NFC combines the interface of a smartcard and reader into a single device.

Radio Frequency ID	Near Field Communication
Uni-directional	Bi-directional
Range up to 100m	Range less than 0.2m
LF/HF/UHF/Microwave	13.56 MHz
Continuous sampling	No continuous sampling
Bit rate varies with frequency	Up to 424 kbit/s
Power rate varies with frequency	<15 milliamperes

Challenges of RFID

RFID is prone to two main issues: reader collision and tag collision. Reader collision, when a signal from one RFID reader interferes with a second reader, can be prevented by using an anti-collision protocol to make RFID tags take turns transmitting to their appropriate reader.

Tag collision occurs when too many tags confuse an RFID reader by transmitting data at the same time. Choosing a reader that gathers tag info one at a time will prevent this issue.