Probably could use a little more info here. Do you already have an antenna? Are planning on just running 1 coax cable into your tv, because that probably won't work. I'm not familiar with FTA satellite but I'm quite familiar with Diplexers and splitters.
Splitters take 1 signal on a coax and send it to 2 different places. Think of the coax as a pipe carrying water. Put a connector on one end and you can run the water to 2 different locations at the same time, albeit with less water pressure.
Diplexers are used in pairs. Think of the same pipe, but on one end there is a diplexer that pumps both oil and water into the pipe. At the other end is another diplexer that separates the oil and water and sends them to the appropriate destinations.
The other thing you'll want to check os that any splitters or diplexers you use are rated for your FTA signal's frequency. OTA and cable typically run at 900 MHz or less and ka/ku satellite systems run between 800MHz and 2300MHz. If you use a splitter or diplexer on one of those systems it could cause a lot of problems when that common splitter has to deal with a 2100MHz signal.
