Introduction to Radio Frequency (RF) Technology[Copy link]
Introduction to Radio Frequency (RF) TechnologyRF (Radio Frequency) technology is widely used in many fields, such as television, radio, mobile phones, radar, automatic identification systems, etc. The special term RFID (Radio Frequency Identification) refers to the use of radio frequency identification signals to identify targets. RFID applications include: ● ETC (Electronic Toll Collection) ● Railway locomotive and vehicle identification and tracking ● Container identification ● Valuables identification, authentication and tracking ● Target management for commercial retail, health care, logistics services, etc. ● Access control management ● Animal identification and tracking ● Vehicle automatic locking (anti-theft) RF (Radio Frequency) refers specifically to electromagnetic waves with a certain wavelength that can be used for radio communications. Electromagnetic waves can be expressed by their frequency: KHz (kilohertz), MHz (megahertz) and GHz (gigahertz). Its frequency range is VLF (very low frequency) or 10-30KHz to EHF (extremely high frequency) or 30-300GHz.
2. Introduction to Radio Frequency Identification (RFID) Technology
RFID is an easy-to-control, simple and practical flexible application technology that is particularly suitable for automatic control. Its unique advantages are unmatched by other identification technologies. It can support both read-only and read-write working modes, without contact or aiming; it can work freely in various harsh environments; and it can perform high data integration. In addition, since this technology is difficult to be counterfeited and invaded, RFID has extremely high security protection capabilities. Conceptually, RFID is similar to barcode scanning. For barcode technology, it attaches the encoded barcode to the target and uses a dedicated scanning reader to use optical signals to transmit information from the barcode to the scanning reader; while RFID uses a dedicated RFID reader and a special RFID unit that can be attached to the target, and uses RF signals to transmit information from the RFID unit to the RFID reader. The RFID unit contains various relevant information about the target, such as: the name of the target, the starting and ending points of the target transportation, the transfer point, and the specific time when the target passes through a certain place, etc., and can also load indicators such as temperature. RFID units, such as tags and cards, can be flexibly attached to various items from vehicles to cargo chassis. The radio frequency used by RFID technology is 50KHz-5.8GHz. As shown in Figure 1, a basic RFID system generally includes the following parts: ● An RFID unit (transponder or card, tag, etc.) that carries information related to the target object ● An antenna that transmits RF signals between the reader and the RFID unit ● An RF transceiver that generates RF signals ● A reader that receives the RF signal returned from the RFID unit and transmits the decoded data to the host system for processing. ● The antenna, reader, transceiver and host can be partially or fully integrated into a whole, or integrated into a few components. Different manufacturers have different integration methods. (In addition to the above basic configuration, the corresponding application software should also be included)
3. Main hardware equipment of RFID system
Transponder (answer machine)/Tag (label, card)
For passive RFID system, in the past, we called the RFID unit that does not actively transmit RF signals to the reader/writer a tag, and the RFID unit that actively transmits RF signals to the reader/writer a transponder. Now the industry no longer strictly distinguishes between these two names, and Tag and Transponder are interchangeable. For the convenience of this introduction, we call the RFID unit that actively transmits RF signals "active" tags, and the RFID unit that only reflects or backscatters RF signals is called "passive" tags. Tags carry relevant information data that can be used to authenticate and identify the target object to which they are attached. Tags can be read-only, read/write, or write one/read multiple; they can be "active" or "passive". Usually, "active" tags require dedicated batteries to support the work of their transmitters and receivers, but the RAM area is not necessarily large. To avoid interference, active tags are required to receive and forward signals at multiple frequencies to avoid interference from adjacent channels. The card is complex and consumes a lot of power. Therefore, "active" tags are generally larger in size and more expensive than "passive" tags. In addition, the service life of "active" tags is directly related to the life of their batteries. "Passive" tags can also be divided into "powered" and "unpowered" working modes according to their applications. "Passive" tags reflect the RF signal transmitted from the reader or transceiver and can add relevant information to the reflected RF signal through modulation and decoding. For "passive" tags, it does not require batteries to amplify the carrier energy of the reverse signal. Some "passive" tags use batteries only to support the work of the memory in the tag or the work of the components in the tag that modulate and decode the reflected signal.
Antenna
Any RFID system should include at least one antenna (whether built-in or external) to transmit and receive RF signals. Some RFID systems use one antenna to transmit and receive at the same time; while other RFID systems use one antenna to transmit and another antenna to receive. The form and number of antennas used should depend on the specific application.
RF Transceiver
RF Transceiver is the source of RF energy. It generates RF signals and RF energy to activate and support (power) the work of "passive" RFID tags. RF transceivers can be integrated and packaged in the reader or exist as independent devices. When used as independent devices, they are generally classified as RF modules. The task of RF Transceiver is to control and modulate and decode the electric frequency transmitted and received by the antenna; filter and amplify the RF signal reflected or backscattered from the "passive" RFID tag. The task of
the reader
RFID reader is to control the RF Transceiver to transmit RF signals: receive the encoded RF signal from the tag through the RF Transceiver, decode the authentication and identification information of the tag; transmit the authentication and identification information together with other relevant information on the tag to the host for processing. Some readers also have other functions. For example, in ETC (electronic toll collection) applications, they include collecting digital input and output information from vehicle detectors, driving barriers, traffic lights and other devices. The hardware part of the reader controls the operation of the reader. Users can issue commands through the relevant control host or local terminal to change or customize its working mode to meet the needs of specific applications. [ip]
Introduction to Radio Frequency (RF) TechnologyRF
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