What is coaxial cable?
Coaxial cable - or just plain "coax", as it's often nicknamed - is a common type of shielded data transmission cable, which is made up of two conductors that are coaxially oriented, but separated by a layer of dielectric insulation. A coaxial cable's anatomy typically unfolds as follows: the core consists of a metal wire (conductor #1), which is then surrounded by a layer of nonconductive dielectric insulation. From there, insulation is covered in metallic mesh, foil or braid (conductor #2), and then the entire cable is wrapped in a protective outer sheathing, or jacket, which holds everything together and locks out moisture and impurities.
What is coaxial cable used for?
Coaxial cable is designed to carry high-frequency signals, and to protect those signals against electromagnetic interference (EMI) from external sources. The most widely recognized use for coax is cable television (CATV), but it's also used in commercial radio communications, ham radio, undersea cable systems, closed-circuit television (CCTV), home video equipment, and broadband Ethernet applications.
What does the "RG" in coaxial cable types like "RG-6" and "RG-59" stand for?
The "RG" is short for "Radio Guide", a term that dates back to the World War II era, when the military made heavy use of coaxial cable, and developed a set of standards to specify different grades of coax and their applications. Even though we still refer to coaxial cables by their original RG numbers today, these standards are now obsolete in regard to actual military use, and have all been brought under the umbrella of current mil spec MIL-C-17.
What's the difference between RG-6 and RG-59 cables?
Both RG-6 and RG-59 cables are widely used in residential settings, especially when it comes to TV. But while RG-59 is the norm for standard Cable (CATV), RG-6 is the coax that has what it takes to transmit digital video signals and satellite TV. When you compare the two types side by side, RG-6 has a larger core conductor, thicker dielectric insulation, and anywhere from 2 to 4 layers of shielding, versus RG-59's one. These physical differences are what make RG-59 best suited to low-frequency transmissions and short cable runs, and RG-6 the ideal choice to carry high frequency signals over long distances.
When it comes to quality, what makes one coaxial cable better than another?
Since better shielding equals less signal interference, it just makes sense that one of the best measures of a coaxial cable's quality is, in fact, its shielding. Types of shielding can vary greatly, as can the amount present from one cable to next – coax typically has anywhere from one to four layers. The best coaxial shields are the ones that offer the highest density, or percentage of cover. Tightly-woven metal braid makes an excellent choice – in addition to being highly conductive, it can provide as much as 95% coverage. For extra protection, some manufacturers combine braid with an additional layer or two of metallic foil, which helps to block small amounts of EMI that often manage to seep into the cable through tiny holes found in the braid.
When it comes to cable quality, conductor materials can be a hotly debated issue. While some manufacturers and A/V enthusiasts will tout the benefits of silver and oxygen-free copper (OFC), the truth is that – used as core conductors – these metals generally don't perform any better than standard or tinned copper. They do, however, sound really high-end, and are great at sending cable markups through the roof. Always trust a cable's specifications over fancy labeling.