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  RF is the abbreviation of radio frequency, which means the electromagnetic frequency that can be radiated into space. RF (radio frequency current) is a kind of high frequency alternating electromagnetic wave. In the theory of electronics, when current flows through a conductor, a magnetic field forms around the conductor. When alternating current passes through a conductor, an alternating electromagnetic field is formed around the conductor, which is called electromagnetic wave. When the frequency of electromagnetic wave is lower than 100 kHz, the electromagnetic wave will be absorbed by the surface and cannot form an effective transmission. However, when the frequency of electromagnetic wave is higher than 100 kHz, the electromagnetic wave can spread in the air and be reflected by the ionosphere at the outer edge of the atmosphere, forming a long-distance transmission capacity. We call the high-frequency electromagnetic wave with the ability of long-distance transmission radio frequency. RF technology is widely used in RF power amplifier test, mobile device / wireless, communication system design and test, wireless infrastructure test, radar design and test, spectrum monitoring / signal intelligence, RF production test, aerospace, military industry, navigation and other fields. In RF industry, the common coaxial connectors are SMA, N type, SMB, SMPM, BNC, TNC, MCX, 7 / 16, i-pex, etc. the coupling mechanisms of coaxial connectors include threaded connection, double bayonet insertion, sliding connection and bayonet connection. RF basic parameters include voltage standing wave ratio (SWR), return loss (RL), insertion loss, also known as attenuation, velocity of propagation (VP), time delay, etc.

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