Shulou(Shulou.com)06/01 Report--

Radio frequency, also known as radio frequency, radio frequency, high frequency, is often used as a synonym for radio, which is an oscillation frequency in the range of 3 kHz to 300 GHz, which is equivalent to the frequency of radio waves and the frequency of alternating current carrying radio signals. WLAN communication technology is a kind of radio frequency technology based on 2.4GHz and 5GHz.

What are the characteristics of RF:

Wavelength, the wavelength of a radio frequency signal is the distance traveled by one cycle.

Frequency, the number of cycles of an RF signal per second is the frequency of the signal, in Hz. Wavelength is inversely proportional to frequency.

Amplitude, a very important attribute of RF signals, can be described as the strength of the signal. The amplitude varies due to attenuation of the signal, but the wavelength and frequency of the signal remain constant.

Phase is generally used to describe the relationship between signals.

What are the characteristics of RF:

Wave propagation is the process of RF signal transmission, that is, the process of moving away from the transmitting antenna.

Absorption, the most common behavior of RF is absorption. If a signal does not reflect back from an object but passes through it, 100% signal absorption is considered to have occurred.

Reflection: When a radio wave hits a smooth object larger than it, the electromagnetic wave reverses direction and propagates in another direction. Generally, objects made of metal reflect electromagnetic waves.

Scattering refers to the phenomenon that light rays are emitted around due to the inhomogeneity of the propagation medium. For example, a beam of light through diluted milk is pink, but from the side and above, it is light blue.

Refraction: When an RF signal passes through media of different densities, it causes the direction of the electric wave to change. This phenomenon is called refraction. Refraction is generally due to atmospheric conditions.

Diffraction (Diffraction) refers to the change of propagation path when the signal passes through an obstacle object, and other waves that do not encounter obstacles still maintain the original propagation path and direction. Diffraction results in an area on the back of the obstacle called the RF shadow, where radio signals are either completely absent or received only weakly.

Loss (attenuation) refers to a decrease in signal strength or amplitude. In the wired part of the wireless communication process, i.e. RF cables, AC current signals lose strength because coaxial cables and other connecting devices have electrical impedance.

Free space path loss, even excluding some of the above factors, according to the laws of physics, a radio wave propagates farther and farther, and the signal strength will become weaker and weaker until the receiver can no longer perceive the existence of the signal.

Multipath, due to the above phenomena of reflection, scattering, refraction, diffraction, etc., the same signal will have multiple transmission paths.

Gain (amplification) increases the amplitude or strength of a signal. There are two types of gain: active and passive. Transceivers and RF amplifiers are active gain devices, while antennas are passive gain devices.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.