There are dozens of different coaxial cable types that are made for a myriad of different applications. Should you get RG-59 or RG-6? And what is RG-6/U? Do you need Quad shielding? What about braiding? Do you need to get Plenum Rated cable? Or Direct Burial? There is a seemingly endless list of options, and picking the wrong type of coax could cause you a world of problems. In this comprehensive article we'll go through the ins and outs of coaxial cable so you always know what you need and when you need it.
What is RG?
Coaxial cables use RG ratings to distinguish between the different kinds of cables. RG is an old, long forgotten military term that stands for “radio guide.” The number distinguishes the different cable specifications, but they are randomly assigned, so don’t look for some type of order in the numbers. Literally dozens of coaxial cables have been made over the years, but the only ones that most people need to worry about are RG 6 cable and RG 59 cable, so those are the two types we are going to focus on here.
RG-6 can also be found with the designation "RG-6/U," but there is no official designation for the U. Some say that it means "universal" or "for general utility use." Others say that it refers to the type of jacket the cable has, but this isn't always the case. For all intents and purposes RG-6 and RG-6/U are the same. If you need a certain type of jacket, make sure and check the specs. But we'll get into different jacket types later on.
RG59 cable has been around for a long time. This cable used to be what most people used for their cable TV connection. However, modern signal requirements have made this cable less popular in the last few years. RG 59 has a smaller conductor than RG 6, which means that it can’t achieve the same signal quality as RG 6. The way its shielding is designed also means that it doesn’t keep Gigahertz level signals inside the conductor very well. This is why RG 59 probably isn’t a good choice for your TV or internet connection.
RG 59 is good for lower frequency signals (anything under about 50 MHz). That makes it a good choice for a closed circuit television (CCTV) video surveillance system. You can even make your installation easier by getting what’s called “Siamese coaxial cable” This cable consists of a RG 59 cable merged together with a 2C power cable. By using this type of cable you can run the power and video for your security cameras simultaneously, effectively cutting your install time in half. Also some older HD TV’s still use lower frequencies (around 37 MHz), making RG 59 a better choice for them.
All of the new demands required by, satellite signals and broadband internet made it necessary to find a more effective coaxial cable. RG6 cable was designed to fulfill these requirements. It has a larger conductor, which gives you much better signal quality. The dielectric insulation was made thicker as well, which means it is much less likely to carry an electric current that could damage your sensitive electronics. RG 6 is also made with a different kind of shielding, which allows it to more effectively handle Ghz level signals.
The Bottom Line
RG 6 is generally a much better choice for your CATV, satellite, TV antenna, or broadband internet. RG 59 is generally better for most CCTV systems. What you really need to consider are the frequency ratings your equipment uses. If your equipment uses higher frequencies (above 50 MHz), then you’ll want to go with RG 6. If your frequencies are lower than that, then you’ll want to use RG 59.
Other Stuff to Consider
Deciding between RG 59 and RG 6 is only part of the process. Each class of cable can have different types of shielding or jacket and may or may not be rated for your chosen installation.
Shielding prevents signal loss, and therefore preserves your signal quality. Coaxial cables usually come with two types of shielding: dual and quad (although some RG 59 cables still use single shielding). The more shielding you have, the better your cable will perform, especially in longer runs. The difference is in the amount of shielding provided. Dual shielding involves a bonded foil shield underneath a metal braid (RG 59 cable uses a copper braid and RG 6 uses an aluminum braid). Quad shielding has more layers of shielding and is usually more protected. However, newer coaxial cables are made with a 95% braid (most braids are only 60%), which allows them to perform better than quad shielded cables.
While newer shielding techniques have allowed us to cut signal loss to a minimum, there is always some signal loss. Here’s the breakdown of signal loss (attenuation) in decibels for 100 ft. of cable. Just remember, the longer your cable runs are, the more signal loss you will experience. That’s why it’s best to keep your installation lengths as short as possible.
RG 59 Signal Loss (in dB) per 100 ft:
Loss at 50 MHz: 2.4 dB
Loss at 100 MHz: 3.4 dB
Loss at 400 MHz: 7.0 dB
Loss at 900 MHz: 11.1 dB
Loss at 1000 MHz: 12.0 dB
RG 6 Signal Loss (in dB) per 100 ft:
Loss at 50 MHz: 1.5 dB
Loss at 100 MHz: 2.0 dB
Loss at 400 MHz: 4.3 dB
Loss at 900 MHz: 6.8 dB
Loss at 1000 MHz: 7.0 dB
Plenum spaces are the open spaces above the ceiling or below the floor that are used for air circulation. Technically, any ductwork is considered a plenum space too. These spaces are important for air circulation in any building, but they also bring some problems if you ever have a fire because of the high oxygen content and lack of fire barriers. Using untreated cables in plenum spaces can spread the fire to other areas very quickly and spread noxious smoke throughout the building. Plenum cables are coated with flame retardant and made using special plastics that don’t smoke nearly as much as other plastics to help prevent this problem. Any cable that you run through plenum spaces must be plenum rated.
Outdoor and Direct Burial Coax
If you are running cable outside, it has to have added protection from the weather and the elements. Outdoor cable has been specially designed to resist the elements. They come with a PE (polyethylene) jacket instead of the standard PVC jacket used in most coax cables. The PE jacket makes this cable extremely resistant to cold weather, moisture, chemicals, abrasion, cutting, and even lightning.
When you bury a coaxial cable, moisture becomes even more of an obstacle. Without added moisture protection, you risk moisture and contaminants entering into the cable and corroding your shielding and conductor. Direct burial cable has the special PE jacket that outdoor coax has, along with a special gel-like substance in the jacket that blocks water and moisture corroding your conductor and damaging your signal.