Essential Guide to RFID

Essential Guide to RFID

by Mike Boehm on September 30, 2022

RFID or Radio Frequency Identification is a form of wireless information transmission that uses radio waves. RFID systems include a radio transponder, receiver, and transmitter. A database contains a list of all products or persons within the system, so when the RFID transponder approaches a receiver, the reader can identify the unique identity of the person or product. Continue reading to learn more about the history of RFID, how RFID works, and its many applications.

History of RFID

Radar technology was first developed in the 1930s by the United States and further improved in the 1940s to identify incoming aircraft. The technological basis of RFID was explored in the 1950s in the form of long-range transponder systems used by the United Kingdom called IFF. Companies like Sensormatic and Checkpoint emerged in the 1960s, creating technologies like EAS or electronic article surveillance. 

In 1973, Charles Walton invented the first true RFID technology and patented his invention. Before his death in 2011, Charles Walton took out ten RFID technology patents. Yet it would be another 30 years before the mass adoption of RFID technology. In the 1980s, RFID solutions were used for toll roads, animal tagging, and early forms of personnel access. IBM researchers developed ultra-high frequency RFID technology in the 1990s, dramatically improving the data transfer and read ranges, but it still remained too expensive for widespread adoption. 

Over 1000 RFID patents had been submitted by the year 2000. Between 2005 and 2015, the RFID market exploded with a valuation increase of $24 billion. Nearly every business and industry are expected to implement RFID technology within the next 20 years.

How does RFID work?

RFID is not as complicated as it first sounds. As reported above, a radio frequency identification system comprises three components. There is also an external database and accompanying software for identifying the tag.

1. Scanning Antenna

The scanning antenna tunes to a specific range of carrier frequencies, from low frequency to super high frequency. Different frequency bands are used for different applications. The RFID antenna propagates the wave in two dimensions, vertical and horizontal. When an RFID tag comes within range of the antenna, electromagnetic energy causes the tag to transmit data using radio waves. The antenna then sends these radio waves to the reader, where it is decoded into digital information. 

2. Transponder

An RFID transponder, also known as an RFID tag, is the most important component. An RFID tag includes an integrated circuit where information is stored and processed and an antenna that receives and transmits a signal. Tags also contain memory, which may be fixed or programmable.


Passive RFID tags lack a battery source and therefore use the electromagnetic energy from the antenna for power. Passive tags are made of an integrated circuit (IC) and antenna. The reading distance is limited to a maximum of 20 feet without a battery, and these tags are limited to only a few components. But there are still advantages to note: 

  • Can last up to 20 years
  • Significantly cheaper than active tags
  • Small and light

Active RFID transponders have an internal battery to power the circuitry for an extended period of time. This internal battery allows active tags to use higher frequencies, between 800 and 950 MHz. Active RFID tags have several advantages: 

  • Can be scanned from long distances, up to 100 feet
  • Increases bandwidth capabilities
  • Performs self-diagnostics
  • Rugged options
  • Can use a more powerful processor, more memory, and more sensors
  • Can use lowered powered readers 

Yet there are a few disadvantages to consider for active RFID tags. Active RFID tags are significantly more expensive than passive tags. A single active tag may cost $20. The battery life of active tags is between 3-5 years, after which the tag must be replaced. Because active RFID tags have larger batteries, they are much larger and heavier than passive tags.

3. Receiver

RFID receivers, also known as RFID readers, connect to the scanning antenna to wireless receive data from the RFID transponder. Readers constrain a two-way radio transceiver, also known as an interrogator. This transceiver sends an encoded radio signal to activate the RFID tag.

4. Database and Supporting Software

RFID data can be stored using any database software. A database may hold the asset’s name, model number, unique serial number, and any other information about the product or personnel. When the reader interrogates the tag, the supporting software knows which product or person is associated with that tag using the database.

How RFID cards work

Types of RFID

RFID systems can be categorized based on the range of frequencies used to communicate data. Three primary categories are usually recognized: low-frequency, high-frequency, and ultra-high frequency. The frequency bands are not strictly standardized, so their ranges may be reported differently in other resources, but the ranges will be similar.

1. Low Frequency (LF)

Low-frequency RFID systems use the 30 kHz to 300 kHz range and have read ranges between 10cm and ½ a meter. Low-frequency RFID tags are better for use around metal or liquids but have a slower read rate than other options. This type of tag has been used in livestock tracking since 1979. It is also commonly used for access control, asset tracking, and in the automobile industry (car immobilizer).

chip and copper antenna of an RFID tag

2. High Frequency (HF)

High-frequency systems used the 3 MHz to 30 MHz range, and the read range can extend up to 1 meter. HF tags can be used around thin metals without inhibiting functionality but cannot pass through dense metals or water. The HF band includes the NFC or near-field communication protocol. This is a global communication standard operating at the 13.56 MHz frequency. HF tags and NFC tags are used throughout the industry because they are inexpensive. High-frequency tag applications include hotel key cards, proximity card payments, and other forms of access control.

Mifare keycard being presented on a hotel room lock

3. Ultra High Frequency (UHF)

Ultra-high frequency RFID ranges from 300 MHz to 3 GHz and offers much longer read ranges up to 12 meters. Most UHF RFID systems use the 860-960 MHz range. UHF tags are sensitive to metals, liquids, and other EM signals but are cheap to manufacture. They are commonly used in the pharmaceutical industry and inventory tracking. Ultra-high frequency RFID technology can use active or passive tags.

RFID tags by frequency and use chart

RFID Format

RFID tags are programmed using a specific format that the RFID receiver recognizes. The format is the structure of the binary data stored in the tag or card. The receiver and card must use the same format for the data to be read. The most common formats are: 

  • Weigand 26-bit
  • Weigand 37-bit
  • Magstripe
  • Nedap XS
  • EM4200, 40-bit
  • HID corporate 1000

Weigand 26-bit RFID Format

The Weigand 26-bit format is the most widely used in industry today for RDIF proximity cards. When using the 26-bit Wiegand format, the card relays a series of 26 numbers in binary form. Because the ID number is 16-bit, there are 65,545 possible ID numbers. This means a company can assign 65,545 unique RFID proximity cards for access control. The facility code is added to provide a higher level of designation across a business. If two businesses merge, some employees may have the same ID number but should have different facility codes, so there are no issues authenticating who is requesting access. The 8-bit facility code means there are 255 possible facility codes. 

The 26-bit format is used in the following card types: ProxCard II, Indala, EM Cards, Kantech XSF, AWID 26-bit, Keri MS, Doorking DK Prox, and H10302.

RFID Use Cases

RFID offers many benefits for industries to improve operational efficiencies. Industries that have already widely adopted RFID include logistics and supply chain, hospitality, agriculture, healthcare, pharmaceutical, automotive, aerospace, energy, and retail. Let’s take a closer look at the most widely implement RFID use cases:

Inventory Management

RFID helps improve inventory management efficiency since RFID tags do not require ‘line-of-sight’ like barcodes do. They can be read in any orientation and at a distance to increase inventory processing. Companies can reduce their distribution center labor costs by reducing their labor force and streamlining inventory check-in, counting, and shipment. But the up-front costs associated with RFID system implementation must be considered.

Access Control

RFID access control systems allow individuals possessing RFID cards, RFID key fobs, or RFID implants to access secured premises. From a business perspective, access control systems allow organizations to assign specific roles to employees and specify which areas they can access. RFID proximity cards can be implemented for: 

  • School access
  • Campus ID card
  • Hotel room entry card
  • Club card
  • ID card to badge into secure areas

Asset Tracking

RFID asset tracking helps organizations track physical assets. RFID tags are attached to assets, like computers, laptops, scanners, servers, printers, radios, and other expensive equipment. Managing and locating assets is a challenge for businesses of any size. As such, RFID asset tracking is commonly implemented by IT departments. 

Payment Cards

In recent years, RFID proximity cards have been widely adopted as forms of payment. Millions of people now use contactless debit and credit cards. These are passive RFID tags powered by the RFID-capable payment terminal. RFID proximity payment cards are viewed as more secure than traditional credit cards because of built-in protections. Cards must be very close to the reader to transfer their information, and a one-time code is issued for each transaction.

Next 10 Years

RFID is experiencing rapid adoption across various industries. In the next ten years, RFID will be ubiquitous in payment cards and other forms. New antenna designs are under research and may improve the range of RF signals. Additionally, memory will increase to allow further storage and use in ‘smart’ applications. And RFID implants are likely to explode in popularity as civilians adopt this technology to streamline their daily lives.