Both RG-6 and RG-11 cables are are coaxial cables (transmission wires for frequency signals) and 75 ohm wires, a designation that denotes the level of electricity travel within them. However, differences between them lead them to be used for different purposes.
The RG-6 is about half the thickness of the RG-11, with a smaller center conductor (the transmitter of satellite and cable signals, as well as measurer of electrical pressure), a smaller shield for reduction of radio frequency interference to refine signals, and a dielectric insulator large enough to reduce the cable's ability to conduct electricity. Perfect for satellite and cable installations, the RG-6 is small and flexible enough for most applications.
The RG-11 is constructed for applications in which low signal loss is of premier importance, and it is actually the thickest of the coaxial cable family. It can operate on frequencies as high as 3 gigahertz (GHz). Thus the RG-11 is perfect for cable runs that require a lot more length and is often used for connections between antennas and HDTV over-the-air receivers. Also, since it can be run for as long as 400 feet without major signal loss, the cable is marked in 2-foot intervals to keep track of its length.
RG-11, however, is nowhere as flexible as RG-6. Thus it is virtually non-existent in normal home applications, instead restricted to backbone cable runs and department stores where flexibility is not a necessity. Moreover, it is extremely hard to find a radio frequency connector big enough to fit its ends.