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Coaxial Cable Selection for CCTV

RG-59/U is a designator for 75-ohm impedance coaxial cable of which there are several varieties,
each having some slightly different characteristics. There are also other 75 ohm cable types, such as
RG-6/U (18 AWG) and RG-11/U (16 AWG). These have larger gauge conductors and are for use
where longer cable runs are necessary.
Two important characteristics of coaxial cable are the gauge, or diameter, of the center conductor, and
the type of shield. A larger diameter center conductor will have less signal loss for a given distance.
Typical gauges available in RG-59 cables are 20 AWG (American Wire Gauge), 22 AWG, and 23
AWG. The number of the gauge and the physical diameter are inversely proportional. That is, 20 AWG
is larger than 22 AWG, etc.
The second characteristic, shielding, is also important. Cable for CCTV use should have a 95%
coverage copper braided shield. The shield must be effective by conducting any externally induced
voltages to ground. A good shield and a good electrical connection to the connector are of prime
concern. It must also have low resistance to reduce differences in ground potentials at either end of
the cable.