Coaxial Cable Technical Specs and Terms
There is a lot to know about cables. Before we get too far, we need to look at the parts of the cable and why they matter.
center conductor
The center conductor marked "D" in the image above carries all the voltages on the cable. It interacts with the rest of the cable to form a complete system. The center conductor can be solid copper or copper-plated steel. Solid copper is only important for voltage-carrying cables, because radio frequency transmissions called the skin effect, such as antenna or satellite signals, don't go all the way through the cable, they just hop around on the outside.
Dielectric
The dielectric marked "C" in the image above is the critical part of the cable. It's more than just preventing the center conductor from touching the outer shield. It is a working part of the system because it is made of a material that polarizes when contacted by voltage. This property, called the dielectric constant, and the thickness of the material itself determine how far the shield must be from the center conductor.
The dielectric constant describes how well a material is polarized, and since polarized materials are better insulators than non-polarized materials, it indirectly describes the insulator quality of any material.
Shield
The shield is the outer layer of metal, marked "B" in the image above. In RG-59 cable, only one shield is required, which is one layer of metal. Most RG-6 cables use a double shield, usually a solid plate with a braided outer layer. Heavy-duty cables use four shields, a solid braid, a sandwich of solid braid, for maximum strength and protection.
The shield provides a ground path for the wire as well as a basic level of protection. A properly constructed braid can add strength to the cable while maintaining flexibility, and can actually provide better protection from stray magnetic fields than thinner layers of foil.
Jacket
The jacket marked "A" in the image above adds structural rigidity to the cable as well as protection from the elements.