The reason why a coax splitter won't work with a satellite feed is twofold. First, you need four satellite receivers if you want a different picture on 4 TVs. Second, each satellite box needs a direct feed from the dish because of the way satellite signals work.
The channels are split in to four groups relating to the the way the signal is beamed down. This means that the satellite LNB on the end of the dish arm is switched between four modes; one per channel group (HL, HH, VL, VH). If you split the satellite signal cable two or more ways then sooner or later two boxes will need to be on different channel groups at the same time. One satellite LNB can't be in two different receiving states at the same time.
Sky's solution was to move to an LNB with 4 outputs. A recording Sky box takes two feeds. Each feed drives one LNB out of the four on the dish arm. This way there's no clash. That's why you see a lot of satellite dishes with two wires connected. The house has a recording box or two boxes that just show live signals.
As already mentioned, you can have one satellite receiver and split the output signal to feed more than one TV. I'll be doing exactly this in a commercial install later in the week. Two older TVs will use the RF outputs. Two new flat panel TVs and a projector will share the HDMI output. They'll all show the same signal, so all will have a window on to the main channel being viewed. In this case that's fine because it's exactly what's required.
Cable TV works in a very similar way to satellite.
Freeview via your TV aerial is the exception, and it's what most people are familiar with and how they first start with the hardware for splitting signals.
The reason that Freeview works through a splitter is because the aerial signal contains all the different channel groups, so it's easy to hop between channels. Second, the tuning apparatus is contained in each TV so there's no need for outboard tuners.
If your main TV feed is via satellite, and you don't want to buy an extra three satellite receivers (or pay for the extra subscriptions), then really the only way to split the signal between four TVs is to take the signal after the satellite box has decoded it and then send the same picture to all the TVs. An aerial splitter will work for this. Depending on the cable lengths involved and the quality of cable (which is more important than people realise until too late), then either an amplified splitter
LINK or a passive splitter
LINK can be used.
A passive splitter is a few pounds cheaper, but it does need a much more powerful signal from the Sky box RF out to survive first the splitting process and then the losses down the cables to the TVs. A safer bet is an amplified splitter. Here there's very little loss in signal strength. It might be £20 or £25 as opposed to £10 or £15, but you won't waste time and money because the signal is too weak. It'll just work.
