What types of coax cabling that have been used in computer networking?

RG-6 (radio grade-6) cable is the most frequently used and distributed coaxial cable around. It is also known as home cable, since it is used in connecting a television set to a Cable Television (CATV) signal distributor. This cable has a single copper conductor surrounded by a copper braided dielectric insulator contained within an outer protective covering. With a standard impedance of 75 ohms, RG-6 is a successor to RG-59 cable, which was used in applications like audio and video transmission.

RG-8 cable, also called 10Base5 Thicknet cable, has a very rugged design, carrying several layers of dielectric material and shielding over its core conductor. RG-8 cables are available with a standard characteristic impedance of 50 to 52 ohms. The central copper conductor has a core diameter of 2.17 mm and frequency response range as high as 500 MHz, making it suitable for radio applications. Compared with RG-6 and RG-59 coaxes, RG-8 cables are not ideal for carrying audio and video signals. RG-8 coaxial cables were succeeded by RG-58 or 10Base2 Thin-net cables, which served as a standard medium in local area networks for a long time.

This type of coaxial cable has two copper or aluminum braids parted by an insulating material. In addition to that, a twinaxial cable has a pair of plastic-coated solid conducting wires at the core, which carry two differential electric voltages in order to fulfill maximum transmission and reception requirements. Different manufacturers have their own standardized twinaxial cables for their particular devices. Twinaxial cables are commonly used in computer networking environments.

Triaxial or triax is a form of coaxial cable which has three protecting shields for a single copper conductor contained at the core. These shields include two copper or aluminum layered meshes, parted from each other through a dielectric insulator. This set of coverings increases the cable's efficiency and effectively decreases the amount of signal leakage and external noise interference. Triaxial cables come in different varieties with respect to impedance and gauges, which makes them highly suitable for electronic applications requiring minimum electromagnetic interference in transmission.

As their name indicates, semi-rigid coaxial cables are inflexible cables with solid conductor covering over the insulator-packed internal conductor. This solid covering provides an additional benefit at higher frequencies, especially on microwave frequencies where skin effect takes place. Skin effect is the quality of electrical signal to flow at the outer levels of a conductor on high frequencies. Semi-rigid coaxial cables are widely used in applications like long-haul data links, which require collection of microwave signals on a physical medium.