Copper is the hard-core of coaxial cable, out-convering a layer of insulating material. The insulating material surrounded with a closely woven mesh conductor, cover with a layer of protective material. There are two widely used coaxial cables. One is 50 ohm cable for digital transmission, as areused for baseband transmission, it is also called baseband coaxial cable; the other is 75 ohm cable for analog transmission, the broadband coaxial cable. This difference is caused by historical reasons, not because of technical reasons or manufacturer.
This structure of coaxial cable makes it have high bandwidth and excellent noise rejection properties. Bandwidth depends on the length of coaxial cable. 1km of cable can reach 1Gb / s ~ 2Gb / s data transfer rate. You can also use a longer cable, but the transmission rate is lowered or use intermediate amplifier. Currently, coaxial cable,are replaced with a large number of optical fiber, but still widely used in cable TV and some local area network.
