Difference between revisions of "Coaxial Cable Data"

Revision as of 08:48, 7 March 2008

A coaxial cable is one that consists of two conductors that share a common axis. The inner conductor is typically a straight wire, either solid or stranded and the outer conductor is typically a shield that might be braided or a foil. The point to coaxial cable is to shield the signal from interference. Open wire carries a signal better, but is subject to so many types of interference, coaxial cable is used as a solution. Coaxial cable is a trade off, the shielding protects the signal from interference, but signal loss is present.

Coaxial cable is used to carry radio signals, video signals, measurement signals and data. There is always some signal radiating from coaxial cable. Hence, the outer conductor also functions as a shield to reduce coupling of the signal into adjacent wiring. More shield coverage means less radiation of energy.

Coaxial cable are typically characterized with the impedance and cable loss. The length has nothing to do with a coaxial cable impedance. Characteristic impedance is determined by the size and spacing of the conductors and the type of dielectric used between them. For ordinary coaxial cable used at reasonable frequency, the characteristic impedance depends on the dimensions of the inner and outer conductors.

Coaxial cable was invented in 1929 and first used commercially in 1941. AT&T established its first cross-continental coaxial transmission system in 1940.

Common Coaxial Cable Types

DS-3

DS3 interconnect cables must be made with true 75 ohm cable and connectors. Use DS-3 Coax Cable to interconnect or crossconnect DS-3 transmission equipment and Digital System Cross-connect (DSX) systems. Cables or connectors which are 50 ohm or which significantly deviate from 75 ohms will result in reflections which will lower the performance of the connection, possibly to the point of it not working. Bellcore standard GR-139-CORE defines type 734 and 735 cables for this application. Due to losses, there are differing distance limitations for each type of cable. 734 has a larger center conductor and insulator for lower losses for a given distance. The BNC connectors are also very important as are the crimping and cable stripping tools used to install them. Trompeter, Cannon, Amphenol, Kings, Canare are some of the true 75 ohm connectors known to work. RG-6 cable will also work, though it does not meet telephony technical standards.

• telephony high speed data

RG-6U 75 Ohm

RG6U, RG-6U. Suitable for CatTV and Satellite small dish signal from LNB. It has low loss at high frequency for cable television, satellite television and cable modems.

Dual RG6/U Quad Shield (RG-6UQ) is ideal for antenna, cable television and satellite installations. Make two cable runs at one time for dual LNB satellite or satellite and antenna installations. This cable is 18AWG copper clad steel center conductor surrounded by a foam polyethylene dielectric. A bonded aluminum foil and 60% aluminum braid over another foil and 40% aluminum braid provide 100% shield coverage. This cable meets specifications for CL1, CL2, CM, CMX and CMG installations. Swept tested to 3GHz to ensure performance at applicable frequencies.

• rf and tv antenna
• satellite lnb signal
• cctv

RG-11U 75 Ohm

Used for long drops and underground.

• cctv

RG-58 Coaxial 50-Ohm

RG58, RG-58. A coaxial cable consisting of a 20 AWG solid .032" bare copper conductor with polyethylene insulation, 95% tinned copper braid shield and PVC jacket. RG-58/U is a specific type of coaxial cable often used for Thin Ethernet (10BASE2) and low-power signal connections. The cable has a characteristic impedance of either 50 or 52 Ω.

This cable is used for radiocommunication and amateur radio, thin Ethernet (10base2) and NIM electronics. When used for Ethernet, it provides a maximum segment length of 185 meters.

Most two-way radio communication systems, such as marine SSB, marine VHF, amateur, police, fire, WLAN Antennas etc., are designed to work with 50 Ω cable.

RG-58 cable can be used for moderately high frequencies. Its signal attenuation depends on the frequency, e.g. from 0.11 dB/m at 50 MHz to 1.4 dB/m at 2 GHz.

• Ethernet / networking
• citizen band radio
• vhf, ham radio

RG-59 75 Ohm

RG59, RG-59. Made of 23 AWG solid copper, shielded with 34 AWG braided annealed copper and wrapped in a PVC jacket. RG-59/U is a specific type of coaxial cable, often used for low-power video and RF signal connections.

Frequently used for lowpass baseband video frequencies, such as composite video. RG-59 coaxial cable is commonly packed-in with consumer equipment, such as VCRs or digital cable/satellite receivers. Manufacturers tend to include only RG-59 cables because of its low cost (when compared to RG-6). However, given the short lengths provided (usually 4-6 feet), this is generally sufficient for its typical use. For broadcast RF (like tv antenna cable) its high-frequency losses are too great to allow its use over long distances.

It will carry baseband video in closed-circuit television. It was once (long ago) used for cable television but the signal loss was too high. Generally it has poor shielding but will carry an HQ HD signal or video over short distances. This cable should not be used for Cable TV.

This cable is also used with IBM 3270 equipment, WANG equipment or Black Box Coax Protocol Converters or Switches.

• composite video (RCA)
• Computer
• cctv

RG-62U 92 Ohm

RG62U, RG-62 U. This cable is most commonly used in automobiles for the car stereo radio antenna.

It is also used for the once popular ARCNET networking system for computers. Original ARCNET used RG-62/U coax cable and either passive or active hubs in a star-wired bus topology, a layout eventually copied by modern twisted pair Ethernet LANs.

Specifications Chart