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. In electronic theory, when current flows through a conductor, a magnetic field will be formed around the conductor. Alternating current passes through a conductor and forms an alternating electromagnetic field around the conductor, which is called electromagnetic wave. When the frequency of electromagnetic wave is lower than 100khz, the electromagnetic wave will be absorbed by the surface and cannot be effectively transmitted. However, when the frequency of electromagnetic waves is higher than 100kHz, electromagnetic waves can propagate in the air and be reflected by the ionosphere at the outer edge of the atmosphere, forming a long-distance transmission capability. We call high-frequency electromagnetic waves with long-distance transmission capability radio frequency. Radio frequency technology is widely used in wireless communication field, and cable TV system adopts radio frequency transmission mode.