Baseband coaxial cable and broadband coaxial cable. The current commonly used baseband cable, the shielding line is made of copper mesh, the characteristic impedance is 50 (RG-8, RG-58); the shielding layer of cable broadband coaxial cable used for aluminum stamping is usually the characteristic impedance is 75 (such as RG-59).
According to the diameter of coaxial cable, it can be divided into coarse coaxial cable and fine coaxial cable. Thick cable is suitable for large local network, it has a long standard distance and high reliability. The cable network must be equipped with transceiver and transceiver cable, so it is difficult to install, so the overall cost is high. On the contrary, thinnet installation is relatively simple, low cost, but the installation process is to cut off the cable ends shall be installed on the basic network connector (BNC), and then connected at both ends of the T connector, so when the joint is much easy to generate bad contact problems, this is one of the most common fault current in the operation of ethernet.
In order to keep the correct electrical characteristics of the coaxial cable, the cable shield must be grounded. At the same time, both ends should have terminals to weaken the signal reflex.
Whether or thinnet thick cable are the bus topology, which is a cable connected with the machine, this machine is suitable for dense environment topology. However, when a contact fails, the fault will cascade to affect all the machines on the whole cable, and the fault diagnosis and repair are very troublesome, so it will be gradually replaced by unshielded twisted pair or optical cable.