What is RG?
RG, or Radio Guide, is the original military specification for coaxial cables. This specification dates back to World War II and is now referred to by the Mil-C-17 standard. The numbers following RG in a part number are generally an indicator of size, referring to the diameter of the cable. Higher RG numbers have a thinner central conductor and vice versa.
Most RG numbers also refer to shielding type, jacket type, and dielectric type (which gives its impedance property). Different types of RG ratings for each type of coax cable help to distinguish the distinct characteristics and specifications of the cable. For example, in the designation RG#/U, the U indicates general utility use.
Different Kinds of RG Cables
It is difficult to make generalizations about different types of RG cables since the numbers in the designation are somewhat arbitrary and are not always indicative of the specific form and function of the cable itself. Therefore, when looking for a coax cable, the most important thing to know is the frequency you are looking to send through the cable.
After you have narrowed down your options with that requirement, you want to look closely at the cable specifications to find exactly what you need. This is especially true when looking at different manufacturers. Many of the standards have become vague, so an RG58B/U could have different characteristics from one manufacturer when compared to another.
The two main types of coax cables are ones with an impedance of 75 Ohm and ones with an impedance of 50 Ohm. Ohm refers to the impedance, which is the measure of resistance in the cable to the flow of electrical energy. Cables with 50 Ohm ratings are used for data and wireless communications while 75 Ohm cables are used for video signals.
RG Cable Characteristics
Each RG cable type offers a variety of capabilities. Below are some of the most common options:
RG6 cable is the industry standard for cable and satellite signal transmission. Its larger conductors provide better signal quality and the thicker dielectric insulation, made with a different kind of shielding, allows more effective handling of GHz level signals. RG6 is a thin cable that can be coiled or bent for residential installations within the ceiling or wall. Applications of RG6 cable include television, internet, and video.
RG11 cable is a thick, inflexible cable used in outside and underground applications to minimize signal loss in long runs. It is more difficult to work with and is a higher gauge than others, which provides more space for signals to transfer. High-definition television is the most common application of RG11 cable.
RG59 cable is a very popular cable in domestic and residential settings. It is similar to RG6 but has an even thinner center conductor. RG59 is ideal for short runs and low-frequency transmissions within the home. It is ideal for CCTV systems applications, is otherwise inferior to RG6 in other applications.
Are RG Coaxial Cables low-loss?
Low-loss coaxial cables are similar to RG coax cables in many aspects. The main difference between a standard RG coax cable and a low-loss coaxial cable is the shielding. Low-loss cable has far better shielding than RG style cable, making it have more low loss characteristics. Low-loss cables also use a solid center conductor, which offers lower attenuation than RG cables with stranded conductors.
Applications for low-loss cables typically include WLAN, cellular, PCS, ISM, and many other wireless applications. Low-loss cable is often used in wireless system installations for any antenna-to-radio setup. It is often referred to by its series number, such as 200-series cable. The series number is typically a rough approximation of the diameter of the cable.
The higher the number, the thicker and heavier the cable and the lower attenuation over the entire length. Higher series numbers are used in cases where the antenna is permanently installed at a distance from the radio. Lower series numbers are used when the antenna is closer, especially in portable setups, and where the weight of the cable is important.