The transmission medium is the physical path between the sender and the receiver in the communication network. Commonly used transmission media can be divided into wired (twisted pair, coaxial cable and optical fiber, etc.) and wireless (radio waves, microwave and infrared, etc.) two categories.
1) Wired transmission medium
Twisted pair can be used to transmit analog or digital signals, commonly used for point-to-point connections, and can also be used for multipoint connections.
There are two basic types of coaxial cable: baseband coaxial cable and broadband coaxial cable. Among them, the baseband coaxial cable is used to transmit digital signals, and the broadband coaxial cable can transmit analog or digital signals. Coaxial cables can be used for point-to-point or multipoint connections.
Optical fibers transmit optical signals that carry user data. Optical fiber has the advantages of low attenuation of optical signal, high bandwidth and strong anti-interference ability.
2) The commonly used wireless media are radio waves and microwaves. Wireless transmission does not need to lay a network transmission line, and the network terminal is convenient to move.