RG-6/U is a common type of
coaxial cable
Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric ( insulating material); many coaxial cables also have a p ...
used in a wide variety of residential and commercial applications. An RG-6/U coaxial cable has a
characteristic impedance
The characteristic impedance or surge impedance (usually written Z0) of a uniform transmission line is the ratio of the amplitudes of voltage and current of a single wave propagating along the line; that is, a wave travelling in one direction in ...
of 75 ohms. The term, ''RG-6'', is generic and is applied to a wide variety of cable designs, which differ from one another in shielding characteristics, center conductor composition, dielectric type and jacket type. ''RG'' was originally a unit indicator
['Mike Meyers' CompTIA Network+ Certification Passport', by Glen E. Clark, edited by Christopher A. Crayton, McGraw-Hill, 3rd Edition, 2009, page 32. "Specific coax types were developed for the Ethernet standard, but a number of radio cables have very similar characteristics, and these so-called radio-grade (RG) cables also became associated with Ethernet."] for bulk radio frequency (RF) cable in the U.S. military's
Joint Electronics Type Designation System
The Joint Electronics Type Designation System (JETDS), which was previously known as the Joint Army-Navy Nomenclature System (AN System. JAN) and the Joint Communications-Electronics Nomenclature System, is a method developed by the U.S. War Depar ...
. The suffix ''/U'' means ''for general utility use''. The number was assigned sequentially. The ''RG'' unit indicator is no longer part of the
JETDS
The Joint Electronics Type Designation System (JETDS), which was previously known as the Joint Army-Navy Nomenclature System (AN System. JAN) and the Joint Communications-Electronics Nomenclature System, is a method developed by the U.S. War Depar ...
system (MIL-STD-196E) and cable sold today under the RG-6 label is unlikely to meet military specifications. In practice, the term ''RG-6'' is generally used to refer to coaxial cables with an 18
AWG (1.024mm) center conductor and 75
ohm
Ohm (symbol Ω) is a unit of electrical resistance named after Georg Ohm.
Ohm or OHM may also refer to:
People
* Georg Ohm (1789–1854), German physicist and namesake of the term ''ohm''
* Germán Ohm (born 1936), Mexican boxer
* Jörg Ohm (b ...
characteristic impedance
The characteristic impedance or surge impedance (usually written Z0) of a uniform transmission line is the ratio of the amplitudes of voltage and current of a single wave propagating along the line; that is, a wave travelling in one direction in ...
.
Applications
A common type of 75 ohm coaxial cable is
cable television
Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with broa ...
(CATV) distribution coax, used to route cable television signals to and within homes. CATV distribution coax typically has a
copper-clad steel
Copper-clad steel (CCS), also known as copper-covered steel or the trademarked name Copperweld is a bi-metallic product, mainly used in the wire industry that combines the high mechanical resistance of steel with the conductivity and corrosion re ...
(CCS) center conductor and a combination aluminum foil/aluminum braid shield, typically with low coverage (about 60%). 75 ohm cables are also used in professional video applications, carrying either base band analog video signals or
serial digital interface (SDI) signals; in these applications, the center conductor is ordinarily solid copper, the shielding is much heavier (typically
aluminum
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...
foil, and 95%
copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
braid), and tolerances are more tightly controlled, to improve impedance stability.
Cables typically have
connectors at each end.
Types
Like most cables, RG-6-style cables are available in several different types designed for various applications, including:
''Plain'' or ''house'' wire is designed for indoor or external house wiring.
"Flooded" cable is infused with water blocking gel for use in underground conduit or direct burial.
''Messenger'' or ''aerial'' may contain some waterproofing but is distinguished by the addition of a steel
messenger wire
An overhead line or overhead wire is an electrical cable that is used to transmit electrical energy to electric locomotives, trolleybuses or trams. It is known variously as:
* Overhead catenary
* Overhead contact system (OCS)
* Overhead equipmen ...
along its length to carry the tension involved in an aerial
drop from a utility pole.
''
Plenum
Plenum may refer to:
* Plenum chamber, a chamber intended to contain air, gas, or liquid at positive pressure
* Plenism, or ''Horror vacui'' (physics) the concept that "nature abhors a vacuum"
* Plenum (meeting), a meeting of a deliberative asse ...
'' wire comes with a Low Smoke Zero Halogen (LSZH) jacket that burns but does not produce toxic smoke. LSZH is typically irradiated PVC. Heating drives off volatiles that leaves the resulting product more heat resistant.
Attenuation/signal loss
Cables attenuate a signal in direct proportion to length. Attenuation increases with frequency due to
skin effect
Skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor such that the current density is largest near the surface of the conductor and decreases exponentially with greater depths in the co ...
.
References
External links
COAX History
{{Telecommunications
Signal cables
Cable television technology
Transmission lines