RF-Radio Frequency Understanding

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RF-Radio Frequency Understanding [Copy link]

1. Radio frequency (abbreviated RF, RF, or just rf) refers to alternating current (AC) with the following characteristics: when this current is applied to an antenna, it will produce an electromagnetic (EM) field suitable for wireless broadcasting and communication. These frequencies cover a large part of the electromagnetic spectrum, ranging from the lowest allocated wireless communication frequency of 9 kHz (which is within the range of human hearing) to several thousand GHz. When RF current is applied to an antenna, an electromagnetic field is generated that propagates through space. This field is sometimes called an RF field; in less technical terms, it is called a radio wave. Any RF field has a wavelength that is inversely proportional to the frequency. In the atmosphere or outer space, f is the frequency in MHz and s is the wavelength in meters, so s=300/f. The frequency of an RF signal is inversely proportional to the wavelength of the EM field in which it is located. If the frequency is 9kHz, then the wavelength in free space is about 33km or 21mi. If it is the highest radio frequency, then its EM wavelength is about 1mm. When the frequency exceeds the RF spectrum range, the EM energy will appear in the form of infrared (IR), visible light, ultraviolet (UV), X-rays, and gamma rays. 2. Radio frequency (RF) is the abbreviation of Radio Frequency, which means the electromagnetic frequency that can be radiated into space, ranging from 300KHz to 300GHz. Radio frequency is abbreviated as RF. Radio frequency is radio frequency current, which is the abbreviation of high-frequency alternating electromagnetic waves. Alternating current that changes less than 1000 times per second is called low-frequency current, and alternating current that changes more than 10,000 times per second is called high-frequency current, and radio frequency is such a high-frequency current. High frequency (greater than 10K); radio frequency (300K-300G) is the higher frequency band of high frequency; microwave frequency band (300M-300G) is the higher frequency band of radio frequency. In electronics theory, when current flows through a conductor, a magnetic field is formed around the conductor; when alternating current flows through a conductor, an alternating electromagnetic field is formed around the conductor, which is called an electromagnetic wave. When the frequency of electromagnetic waves is lower than 100khz, the electromagnetic waves will be absorbed by the surface and cannot form effective transmission. However, when the frequency of electromagnetic waves is higher than 100kHz, the electromagnetic waves can propagate in the air and be reflected by the ionosphere at the outer edge of the atmosphere, forming long-distance transmission capabilities. We call high-frequency electromagnetic waves with long-distance transmission capabilities radio frequency; radio frequency technology is widely used in the field of wireless communications, and cable television systems use radio frequency transmission.

月下良缘

Thanks for sharing!

eastin8

Thanks for sharing. RF, come find me

175868147

Thanks for sharing!

keli55

I just started learning, thanks