Coaxial cables can be divided into two basic types, baseband coaxial cable and broadband coaxial cable. At present, the baseband is a commonly used cable, and the shielded wire is meshed with copper, and the characteristic impedance is 75 (such as RG-8, RG-58, etc.); the shield of the commonly used cable for broadband coaxial cable is usually aluminum. Stamped, the characteristic impedance is 50 (such as RG-59, etc.).
Coaxial cables can be divided into thick coaxial cables and thin coaxial cables according to their diameter. The thick cable is suitable for relatively large local networks. It has a long standard distance and high reliability. Since the cable does not need to be cut during installation, the computer can be flexibly adjusted according to the needs. However, the thick cable network must be equipped with a transceiver cable. It is difficult, so the overall cost is high. On the contrary, the installation of the thin cable is relatively simple and the cost is low. However, since the cable is cut during the installation process, the basic network connector (BNC) must be installed at both ends, and then connected to the T-connector, so that when the connector is long, it is easy to cause bad. Hidden danger, this is one of the most common failures that occur in Ethernet currently in operation.
Whether the thick cable or the thin cable is a bus topology, that is, a cable is connected to multiple machines. This topology is suitable for machine-intensive environments, but when a contact fails, the fault will affect the entire cable in series. All the machines on it. Fault diagnosis and repair are cumbersome and will therefore be gradually replaced by unshielded twisted pair or fiber optic cable.