Coaxial cable designations start with the letters "RG," which originally meant "radio guide," but some technicians today use the term "radial ground." The electronic signal travels over a single center conductor and an outer shield, made of either foil or braided wire, protects the signal from interference. RG-59 and RG-6 are only two of many coaxial cable designation codes, ranging between RG-4 and RG-405, with the number rising as companies develop more specialized cable types.
Coaxial Cable Construction
The center conductor of coaxial cable is usually copper, but can be aluminum or a combination of metals. Stranded center conductors offer greater flexibility, but solid conductors have less loss. The shield can be copper or aluminum foil, or braided wire. Some cables use both, and some cables add a second shield. The insulating material between the conductor and the shield varies from Teflon to various types of plastics to change insulation capacity, flexibility, durability and cost. The outer jacket material can vary to allow extreme temperature or weather use.
RG-59
RG-59 has a 20-gauge solid copper center conductor and a single braided copper shield. At 1000 MHz, RG-59 has a loss of 12 decibels (dB) per 100 feet, an inductance of .131 microhenrys (uH) and a capacitance of 20.5 picofarads (pF) per foot. It has a DC resistance of 49.0 ohms per 1000 feet on the center conductor and 2.6 ohms per 1000 feet on the shield.
RG-6
RG-6 has an 18-gauge solid copper center conductor, a braided copper shield and an additional foil shield. At 1000 MHz, RG-6 has a loss of 7 dB per 100 feet, an inductance of .097 uH and a capacitance of 16.3 pF per foot. It has a DC resistance of 6.5 ohms per 1000 feet on the center conductor and 9 ohms per 1000 feet on the shield.
Uses
Although RG-6 has a better frequency response and overall loss characteristics, the type of shielding better determines the usage. The second shield of the RG-6 cable does little to protect from interference at under 50 MHz. Over 50 MHz, the shield becomes more effective. Therefore for applications below 50 MHz, such as the 37 MHz signal of HDTV, RG-59 is the better choice. For above 50 MHz, such as for broadband CATV or a satellite system, RG-6 performs better to reduce interference.
Tags: center conductor, 1000 feet, ohms 1000, ohms 1000 feet, 1000 feet center
