Coaxial Cable Facts

Coaxial cable is an older technology that is usually implemented with a bus topology. It is not suitable for ring or star topologies because the ends of the cable must be terminated. It is composed of two conductors, which share a common axis, within a single cable.

Coaxial cable is built with the following components:

Two concentric metallic conductors:
- The inner conductor, which carries data signals. It is made of copper or copper coated with tin.
- The mesh conductor is a second physical channel that also grounds the cable. It is made of aluminum or copper coated tin.
The insulator, which surrounds the inner conductor, keeps the signal separated from the mesh conductor. It is made of PVC plastic.
The mesh conductor, which surrounds the insulator and grounds the cable. It is made of aluminum or copper coated tin.
The PVC sheath, which is the cable encasement. It surrounds and protects the wire. It is made of PVC plastic.

Coaxial cable has the following advantages and disadvantages:

Advantages	Highly resistant to EMI (electromagnetic interference) Highly resistant to physical damage
Disadvantages	Expensive Inflexible construction (difficult to install) Unsupported by newer networking standards

The table below describes the different coaxial cable grades.

Grade	Uses	Resistance Rating
RG-58	10Base2 Ethernet networking (also called Thinnet)	50 ohms
RG-59	Cable TV and cable networking	75 ohms
RG-6	Cable TV, satellite TV, and cable networking RG-6 has less signal loss than RG-59, and is a better choice for networking applications, especially where longer distances (over a few feet) are involved.	75 ohms
RG-8	10Base5 Ethernet networking (also called Thicknet)	50 ohms

Note: When using coaxial cables, it is important to use cables with the same resistance (impedance) rating.

The table below describes the types of connectors used with coaxial cable.

Connector	Description
F-Type	Twisted onto the cable Used to create cable and satellite TV connections Used to hook a cable modem to a broadband cable connection
BNC	Molded onto the cable Used in 10Base2 Ethernet networks
AUI	DB15 serial connector Used in 10Base5 Ethernet networks