Radio frequency application

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Radio Frequency (RF) is the abbreviation of radio frequency, which means electromagnetic frequency that can radiate into space, and the frequency range is from 300 kHz to 300 GHz. Radio frequency is abbreviated as RF current, which is the abbreviation of high frequency AC electromagnetic wave.

Alternating current that changes less than 1000 times per second is called low-frequency current, and that that changes more than 10000 times is called high-frequency current, and radio frequency is such high-frequency current. High frequency (greater than10k); Radio frequency (300K-300G) is the higher frequency band of high frequency; Microwave band (300M-300G) is the higher frequency band of radio frequency.

Extended data:

principle of operation

The basic workflow of the system is as follows: the reader sends a radio frequency signal with a certain frequency through the transmitting antenna, and when the radio frequency card enters the working area of the transmitting antenna, it generates an induced current and activates the radio frequency card by obtaining energy; Radio frequency cards send their own codes and other information through the card's built-in transmitting antenna.

The system receives the carrier signal sent by the RF card by the antenna and transmits it to the reader through the antenna regulator. The reader demodulates and decodes the received signal and sends it to the background main system for relevant processing. The main system judges the legitimacy of the card according to the logical operation, carries out corresponding processing and control for different settings, and sends out command signals to control the actions of the actuator.

The read-write distance of RFID system is a key parameter. At present, the price of long-distance RFID system is still very expensive, so it is very important to find ways to improve its reading and writing distance.

The factors that affect the reading and writing distance of radio frequency card include antenna working frequency, RF output power of card reader, receiving sensitivity of card reader, power consumption of radio frequency card, Q value of antenna and resonant circuit, antenna direction, coupling degree between card reader and radio frequency card, energy obtained by radio frequency card itself and energy for sending information, etc. The reading distance and writing distance of most systems are different, and the writing distance is about 40% ~ 80% of the reading distance.

Reference source:

Baidu encyclopedia-radio frequency

China HowNet-Application of Radio Frequency Technology