Why satellite tv connect only one tv at a time whether dish cabal conect many tv at a time?

Answer 1

You can connect many TV's to a single satellite receiver, but they all get the same picture.

I presume you mean why satellite receivers only get one station at a time, while a cable can carry many stations.

A cable can carry many frequencies, just like space they can all exist at once. The multiple signals can be passed through one receiver to the next, each one tuning in to an individual station. VHF and UHF signals can exist together on the same cable.

A satellite dish needs to select between two different streams of signals. Some are sent in a horizontal polarization and others in a vertical polarization.

The LNB (Low Noise Block) at the focus of the dish, has to choose between the two streams of signal. These signals are changed by applying and intermediate frequency into a block of channels at a lower frequency. (Hence the name block)

This is done by sending different voltages back up the aerial coax. This selects the polarization. So you can see that depending on which channel you select on the front panel will change the voltage, so limits which channels you can get.

You can get LNB's with multiple outputs, which separately tune in. You will have multiple cables and have to have individual tuner boxes.