What is a typical cable impedance?
The most typical impedance for coaxial cable are 50 ohms and 75 ohms.
50Ω coaxial cable is probably the most common in use, which generally used in radio transmitters and receivers, laboratory equipment, Ethernet and other environments.
Another commonly used type of cable is 75Ω coaxial cable, which generally used in video transmission, limited television network, Antenna feeders and long distance telecommunications applications and other occasions.
Another commonly used type of cable is a 75 ohm coaxial cable, which is typically used in video transmission, cable television networks, antenna feeders, long distance telecommunications applications and the like.
Why the impedance for coaxial cable is generally 50Ω or 75Ω?
It’s just a choice, and the circuit is a bit of a relationship. Everybody has formed a norm in the long-term work, rises to the national or the international standard. With the standard, we use the standard parameters to design and manufacture of devices, then the future generations in the design of the circuit will follow this standard.
For example, if you design a circuit that is not 50Ω or 75Ω, you will not be able to buy a matching cable or other parts. Then how do you implement your circuit? That’s why we should follow the standard. This 50Ω is definitely related to manufacturing, such as dielectric constant, size, etc.
The impedance of the coaxial cable is mainly used to reduce the noise interference. For example, if the video cable is set to an impedance of 75Ω, the wire of this size can well attenuate the interference of external and internal electromagnetic waves to the video signals in this frequency band.