RFID systems can be decomposed according to the frequency bands in which they operate. There are two main types of systems-passive and active RFID.

RFID systems and frequencies

RFID systems can be broken down by the frequency band within which they operate: low frequency, high frequency, and ultra-high frequency. There are also two broad categories of systems—passive and active RFID. In the sections below we will explore the frequencies and types of RFID systems.

How to classify RFID systems?

RFID systems are usually classified according to their operating frequency bands. Frequency refers to the size of radio waves used for communication between system components. RFID systems around the world operate in low frequency (LF), high frequency (HF) and ultra high frequency (UHF) frequency bands. Radio waves behave differently on each of these frequencies, and the use of each frequency band has its advantages and disadvantages.

For example, if an RFID system runs at a lower frequency, its data reading rate will be slower, but its ability to read near or on metal or liquid surfaces will increase. If the system runs at a higher frequency, it usually has a faster data transmission rate and a longer reading range, but it is more sensitive to radio wave interference caused by liquids and metals in the environment. However, recent technological innovations have made it possible to use UHF RFID systems around liquids and metals.

Low Frequency (LF) RFID

The LF band covers frequencies from 30 KHz to 300 KHz. LF RFID systems usually operate at 125 KHz, but some operate at 134 KHz. This band provides a short reading range of 10 cm, and the reading speed is slower than high frequencies, but it is less sensitive to radio wave interference.

LF RFID applications include access control and livestock tracking.

The standards for the LF animal tracking system are defined in ISO 14223 and ISO/IEC 18000-2. Due to slightly different frequencies and power levels around the world, the low frequency spectrum is not considered a truly global application.

High Frequency (HF) RFID

The HF band ranges from 3 to 30 MHz. The operating frequency of most HF RFID systems is 13.56 MHz, and the reading range is between 10 cm and 1 m. HF systems are moderately sensitive to interference.

HF RFID is commonly used in ticketing, payment and data transmission applications.

There are multiple HF RFID standards, such as the ISO 15693 standard for tracking items, and the ECMA-340 and ISO/IEC 18092 standards for Near Field Communication (NFC), which is a short-range technology commonly used for data exchange. equipment. Other HF standards include the ISO/IEC 14443 A and ISO/IEC 14443 standards for MIFARE technology for smart cards and proximity cards, and the JIS X 6319-4 brand for FeliCa, a smart card system commonly used in electronic money.

Ultra High Frequency (UHF) RFID

The UHF band covers the range of 300 MHz to 3 GHz. The RAIN RFID system complies with the UHF Gen2 standard and uses the 860 to 960 MHz frequency band. Although there are some differences in frequencies in different regions, RFID systems in most countries/regions operate between 900 and 915 MHz.

The passive UHF system has a reading range of up to 12 m, and UHF RFID has a faster data transmission rate than LF or HF. UHF RFID is the most sensitive to interference, but many UHF product manufacturers have found ways to design tags, antennas, and readers to maintain high performance even in harsh environments. Compared with LF and HF tags, passive UHF tags are easier to manufacture and lower cost.

RFID has a wide range of applications, from retail inventory management to anti-counterfeiting drugs to wireless device configuration. Most new RFID projects use UHF instead of LF or HF.

The UHF band is regulated by a single global standard called the ECPglobal Gen2 (ISO 18000-63) UHF standard. Impinj pioneered the development of the Gen2 standard, lobbyed the government to allocate spectrum, and co-founded the RAIN RFID alliance with Google, Intel, and Smartrac to promote

 The widespread adoption of technical solutions in many different vertical markets.

Active RFID system

In an active RFID system, the tag has its own transmitter and power supply. Usually, the power source is a battery. Active tags broadcast their own signals to transmit information stored on their microchips.

Active RFID systems usually operate in the ultra-high frequency (UHF) frequency band and provide ranges up to 100 m. Generally, active tags are used for large objects, such as rail cars, large reusable containers, and other assets that require long-distance tracking.

There are two main types of active tags: transponders and beacons. The transponder is "awakened" when it receives a radio signal from the reader, then it is powered on and responds with a return signal. Since transponders do not actively radiate radio waves until they receive a signal from the reader, they can extend battery life.

Beacons are commonly used in real-time location systems (RTLS) to continuously track the precise location of assets. Unlike transponders, beacons are not powered by the reader's signal. Instead, they send out signals at preset intervals. Depending on the level of positioning accuracy required, the beacon can be set to emit a signal every few seconds or once a day. The signal of each beacon is received by the reader antenna located around the monitored area and conveys the ID information and location of the tag.

The customer's wireless ecosystem is very large and growing every day. Some use cases deploy active RFID and passive RFID at the same time to increase asset or sensor management methods.

Passive RFID system

In a passive RFID system, the reader and reader antenna send radio signals to the tag. The RFID tag then uses the transmitted signal to turn on the power and reflects the energy back to the reader.

Passive RFID systems can operate in low frequency (LF), high frequency (HF) or ultra high frequency (UHF) radio frequency bands. Since the range of passive systems is limited by the power of the tag backscatter (radio signal reflected from the tag back to the reader), they are usually less than 10 m. Because passive tags do not require a power supply or transmitter, only a tag chip and antenna, they are cheaper, smaller, and easier to manufacture than active tags.

Passive tags can be packaged in many different ways, depending on the specific RFID application requirements. For example, they can be mounted on a substrate or sandwiched between an adhesive layer and paper tags to create smart RFID tags. Passive tags can also be embedded in various devices or packaging to make the tags resistant to extreme temperatures or irritating chemicals.

Passive RFID solutions can be used in many applications. They are usually deployed to track goods in the supply chain, inventory products in the retail industry, verify drugs and other products, and embed RFID functions in various devices.

Battery-assisted passive (BAP) system

A battery-assisted passive RFID tag is a passive tag that combines key active tag functions. Although most passive RFID tags use energy from the RFID reader signal to power the tag chip and backscatter to the reader, BAP tags use an integrated power supply (usually a battery) to power the chip, so all the energy captured comes from the reader Can be used for backscattering. Unlike the transponder, the BAP tag does not have its own transmitter.