(In a network engineering communication system, a transmission medium is required between computers and network devices to connect and transmit information and data. If the computer on the network is compared to a cargo station, and the data information is a car, then the network transmission medium is an indispensable road. Nowadays, the transmission media of computer data communication include wired media (twisted pair, copper coaxial cable, optical fiber) and wireless media (radio waves, infrared rays and microwaves).)