You might have heard there are two types of coaxial cables… those with a center conductor made out of solid copper, and those with a center conductor that is steel with a thin skin of copper. You’d be forgiven for thinking that copper-clad steel (as they call it) is a ripoff and you should never use it. That’s not 100% true.
There are two things you need to know when you talk about cables and their center conductors. The first thing is that the RF transmission that makes up your satellite picture only travels on the outside of the center conductor. This is known as the “skin effect” and it is one of the basic principles of RF theory. So, if all you’re carrying is RF, it doesn’t matter what the whole cable is made of.
The second thing you need to know is that copper is pretty expensive these days, so there’s a tendency to want to use as little as possible of it. The size of the center conductor is dictated by the RG6 standard, so it’s not going to change. The solution is to take a steel wire and copper-plate it. It really does work just as well, and copper-clad steel is used all the time for cable TV installations.
On the other hand, if you are carrying power as well as signal for any reason, you need solid copper core for your center conductor. Electricity travels much better through copper than steel, and if you’re putting voltage through that wire, it had better be copper simple as that.
Why would you put power through a coax cable? DIRECTV uses a power inserter to power its multiswitches, and all satellite dishes need power for the LNB module. Antenna amplifiers and rotators need power, and so do mobile dishes. There are a lot of reasons power would travel through a coax cable. Since the power travels through the center and the signal travels only on the edge, there’s no reason not to, really. Why run another wire if you don’t need to?
DIRECTV and DISH specify that solid copper core RG6 cable be used throughout satellite installations, on every single cable, but if you are doing it yourself you can save quite a bit of money using copper-clad steel cables for the lines between the splitter and the multiswitch. Just remember to use solid copper core RG6 for lines that will carry power, such as a line from a power inserter or any line that goes straight to the dish itself