Coaxial cable, or coax as it is commonly referred to, has been around for a long time. Coax found success in both TV signal transmission as well as in network implementations. Coax is constructed with a copper core at the center that carries the signal, plastic insulation, braided metal shielding, and an outer plastic covering. Coaxial cable is constructed in this way to add resistance to attenuation (the loss of signal strength as it travels over distance), crosstalk (the degradation of a signal caused by signals from other cables running close to it), and EMI (electromagnetic interference). Figure 2 shows the construction of coaxial cabling.

Figure 2 Coaxial cabling.

Networks can use two types of coaxial cabling: thin coaxial and thick coaxial. Both have fallen out of favor, but you might still encounter thin coax in your travels.

Thin Coax

Thin coax is much more likely to be seen than thick coax in today's networks, but it isn't common, either. Thin coax is only .25 inches in diameter, making it fairly easy to install. Unfortunately, one of the disadvantages of all thin coax types are that they are prone to cable breaks, which increase the difficulty when installing and troubleshooting coaxial-based networks.

There are several types of thin coax cable, each of which has a specific use. Table 2 summarizes the categories of thin coax.

Table 2 Thin Coax Categories



RG-58 /U

Solid copper core

RG-58 A/U

Stranded wire core

RG-58 C/U

Military specification


Used for cable TV and cable modems