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See also Coax Termination

Coaxial Cable (coax) is the most popular type of transmission line for TV, CB and amateur radio. 300 ohm twin lead is also popular.

The coax connects the receiver or transceiver to the antenna, dish or commercial Cable TV line.

Coaxial Cable can come in many grades based on the type of shield, conductors and diaelectric.


Other pictures at West Penn Wire
Foam dielectric - More flexible, higher Velocity of Propagation.
Stranded core - more flexible.
larger core - lower resistance, and attenuation.
Shielding - Layers and quality reduce noise and signal leakage.


The most common use of triaxial cable is in television industry as a connecting cable between a camera and its Camera Control Unit (CCU).
Type ohms
Ω
diam (in.) Attenuation dB / 100 ft.2 Vel. of Prop-
agation
1
Uses Price
28
MHz
100 MHz 2 m HAM band (145MHz) 400 MHz 12962.4
GHz
RG-8/U 50 0.405 0.98 1.3-2.1 3 dB       66-82% Ham Radio, Thick Ethernet 64-88 ¢/ft
RG-8/X 50 0.155 1.5 3.0-4.0 4 dB 8.4   22 78-82%   26-38
RG-58/U 50 0.195 2.2 3.8-4.8 4.5 dB 11.8   35 66-78% Ham Radio, Thin Ethernet 18
RG-58A/U 50 0.195 2.4 4.5-5.2 5 dB       66-78 % Ham Radio, Thin Ethernet 22
9913       1.4 1.6 2.7 5        
RG-213/U 50 0.405 1.2 2 2.8 5.1 10   66% Ham Radio 17
RG-174/U 50 0.068   8.4 10.1 17.0 31.4     Ham radio  
LMR-195 50 3/16     4.4 7.3   18.6   This is a drop in replacement for RG-58 & RG-142
LMR-200 50 3/16     3.9 6.6   12.6-
16.5
  It features a 1/2 inch bending radius and a lower loss than any other coax cables in the same class.
LMR-240 50 1/4     3.0 5.0   12.7
LL 400
LMR-400
50 0.405 0.67   1.5 2.5 4.8 6.65   Low loss Coax, Solid Ctr Conductor 80
LMR-500          
LMR-600 50 0.59   0.9 0.95 1.6   4.43     
LMR-900-DB 50 .87     0.65 1.1   2.9
Type ohms
Ω
diam (in.) Attenuation dB / 100 ft.2 Vel. of Prop-
agation
1
Uses Price
28
MHz
100 MHz 2 m HAM band (145MHz) 400 MHz 12962.4
GHz
Most cable TV and Internet use RG-6U or RG-59U 3
RG-6/U 75 0.3324   2.0-2.3   4.3 6.1   -82% CATV, Satellite TV. Runs over 175 ft.  
RG-59/U 75 0.2 1.8 2.9-3.4   7 12   66-82% TV 17
RG-11/U 75 0.405 1.15 1.4-1.5   3.4 6.6   66-82% Long TV drops and underground. Runs over 175 ft. 52
Twin Lead 300       0.75 dB            
H155                   lower loss at high frequency for radiocommunication and Ham radio
1. Vel. of Propagation: Lower number is generally for solid dielectric and higher number for foam (gas injected) dielectric (lower dielectric constant). see below.
2. Attenuation - smaller is better

3. 
Type AWG
RG  6 18 AWG
RG 59 20 AWG

4. Belden standard shield RG6/uC ATVis .274 in in diameter
   Belden Quad Shield RG6/u CATV Coaxial Cable is .294 in in diameter


The U designation is ambiguous.  It sometimes indicates core type.
U - Solid Core
A/U - Stranded Core

3dB loss represents 1/2 the original signal
Specs within a cable type vary based on conductor size, construction and dialectric type.

Several standards organizations rate cable in a variety of areas.
For low voltage cables (COAX) flame retardent properties are important.
polyvinyl chloride (PVC) and polyethylene (PE). Underwriters Laboratories (UL) - Wire and Cable Marking and Application Guide

Solid copper vs copper clad steel CCS) center conductor:
The TV signal is Radio Frequency (RF) only travels on the outside of the center conductor. This is known as the "skin effect". So CCS is fine.
Some sytems put direct current thru the cable to power amplifiers or rotators. DirectTV uses power to power its multiswitches and most satellite systems use power for their Low Noise Block downconverter (LNB), so they usually specify solid copper.

Frequencies for CATV and satellite TV:
no CATV system goes beyond 1GHz
Satellite systems use frequencies around 2.4GHz
Conductor
AWG
Dielectric Diameter
in
Attenuation
@ 100 MHz
Vp
RG-8/U
13 Stranded Gas Injected PE .405 1.8 dB 82%
13 Stranded Foam FEP .352 1.4 82
10 Stranded Gas Injected PE .405 1.5 82
RG-8/X
16 Stranded Gas Injected PE .242 3.1 82
RG-58/U
20 Stranded Foam PE .195 4.8 78%
20 Solid Foam PE .195 4.1 78
20 Stranded Foam FEP .158 3.1 82
Source: West Penn Wire

Frequencies

40 m ham =  7 MHz
10 m ham = 29 MHz
      CB = 27 MHz (11 m)
  VHF TV = 54-88 MHz (4.3 m), 174-216 MHz (1.5 m)
 2 m ham = 144-148 MHz
  UHF TV = 470-806 MHz
Satellite TV = 950 to 1450 MHz - The higher frequency satellite signals
  are converted by the Low Noise Block Converter (LNB) at the dish
  to L-Band (1 GHZ) for transmission to the receiver.
Velocity Factor of Propagation (Vp) Through Coaxial Cable
Source: HamUniverse.com

The velocity factor is the speed at which an RF signal travels through a material compared to the speed the same signal travels through a vacuum. The velocity of propagation is inversely proportional to the dielectric constant. Lowering the constant increases the velocity.
Generally, the higher the velocity factor, the lower the loss through a coaxial cable.

General Rules for Coaxial Cable
D = diameter of insulation under the shield
d = diameter of inner conductor.

Velocity Factor, Velocity of Propagation, Vp
The higher the velocity factor, the lower the loss through the cable.
Raising the D/d has no effect on Vp
Raising the dielectric constant lowers Vp

Capacitance
Raising the D/d ratio lowers capacitance
Raising the dielectric constant raises capacitance
Impedance Raising the D/d radio raises impedance
Raising the dielectric constant lowers impedance

Attenuation or Loss
Raising the D/d ratio lowers attenuation
Raising the dielectric constant raises attenuation

Back to Antenna Lab
Stranded wire core is more flexible.
Solid or Stranded doesn't affect Propagation factor
Some cables use copper covered steel (CCS) for strength.
Quad cable (two layers of foil and braid) is not necessairly better depending on the quality of the foil and braid.

Glossary:

attenuation- Signal loss
CATV - Community Antenna television
  Television service to homes via radio frequency signals sent through fixed
  optical fibers or coaxial cables as opposed to over-the-air radio waves.
CCS - Copper Coated Steel
CCTV - Closed-circuit television
     Typically used for surveillance cameras.
CFEP - Cellular Fluorinated Ethylene/Propylene copolymer
CL2 - Class 2 cable - low voltage (NEC Type)
CL2P - Class 2 plenum rated
CM - Communications Cable
dielectric constant - relative permittivity or 
  a measure of how well the material insulates electrically.
FEP - Fluorinated Ethylene/Propylene copolymer (Teflon®)
HD-SDI - High Definition SDI
MP - Multipurpose cable
LL - Low Loss (same as LMR) 
LMR - standard is a UV Resistant Polyethylene jacketed cable designed for 20-year service
         outdoor use. The bending and handling characteristics are significantly better
         than air-dielectric and corrugated hard-line cables.
         LLMR® is a trademark of Times Microwave Systems.
MATV - Master Antenna TV
NEC - National Electric Code
 Article 800 covers multi-purpose and communication cable.
 Article 820 covers community antenna television and RF cable. CATV cable
substituted with multi-purpose or communication listed coaxial cable.
Article 800
   800-3(b)1       CMX     Communications cable limited use
   800-3(b)1       CM      Communications cable
   800-3(b)2       CMR     Communications riser cable
   800-3(b)3       CMP     Communications plenum cable
OF - 
PE - Polyethylene (Solid and Foam)
PU - Polyurethane
PVC - Polyvinyl Chloride
SBC - Solid Bare Copper
SDI - Serial Digital Interface (TV)
Vp - Velocity Factor, Velocity of Propagation
STC -  Stranded tin copper
See: Glossary of terms - Coax at Belden

See Also:
Attenuation & Power Handling Calculator at TimesMicrowave.com
Ham Radio Coaxial Cable Power Handling and Loss Specifications
electromagnetic spectrum
CCTV Cable and Differences in Coaxial Cables at West Penn Wire
Attenuation at QSL
Coax Attenuation Chart at W4RP
Attenuation Chart at Davis RF wire
Coaxial Cable at TWAcomm.com
Coaxial Cable at ElectroCables.com
wire
Video Cables from the Inside Out

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last updated 4 Oct 2008