What is Coaxial?

Coaxial cable is familiar to almost everyone through its household use in transmitting television signals. But coaxial cable is really a much broader category, of which the RG6 television coaxial cable is only one (albeit significant) type. Coaxial cables are comprised of an inner conductor, surrounded by an insulating layer, surrounded by a layer of conductive shield, housed in an insulating jacket. The interaction between the inner conductor and the outer shield contains the electromagnetic field, allowing for long-distance transmission with limited interference. Coaxial cables typically terminate in an RF connector.

The inner conductor of a coaxial cable is most often either copper or copper-covered steel.

The dielectric insulator (sometimes shortened to simply "dielectric") can be made from solid plastic (polyethylene or teflon), a foam insulator (gas-injected foam polyethylene), or air/gas with structural spacers.

The second conductive layer or shield comes in many varieties. In terms of general construction the shield is made from either braided copper or braided aluminum conductors. This braid provides only partial coverage, which is noted by a percentage. Often, a second layer of foil is added to increase coverage. Belden has a line of shielding called Duobond®, which alternates aluminum foil with a braid. II has a foil/braid combo, while IV has a foil/braid/foil/braid combo. See below for a summary of the shield constructions for each coax type.

Insulating jackets are typically made from PVC. All types are available as plenum.

Here is a table of the different types of coax cable available from ShowMeCables and their characteristics:

RG Type (Impededance) Use Conductors Shield
RG-6 (75 Ohm) Household television, CATV, SatelliteTV Copper-clad steel or solid copper
  • 60% braid-100% foil
  • 95% braid
  • Quad, alternating aluminum braid and foil
RG-8 (50 Ohm) Amateur radio or 10BASE5 (thicknet) Solid or bare copper
  • Duobond II® + tinned copper braid shield (95%)
  • 100% Aluminum & 90% Tinned-copper Braid
RG-11 (75 Ohm) Outdoor and long distance Bare copper-covered steel
  • Duobond® + aluminum braid shield (60%)
  • Duobond® IV quad shield (60% and 40%)
  • 60% Braid/100% Foil
  • 100% Foil
RG-58 Radio communication or 10BASE2 (thinnet) Solid copper
  • Solid braid shield
  • Stranded foil & braid shield
RG-59 Closed-circuit television Bare or solid copper
  • 95% copper braid shield
  • Foil and braid shield
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