That is a better antenna. Not an amplifier.
It is an antenna to have outside in a higher signal area to pick up the signal from the tower. This signal will be greatly reduced inside as the building material absorbs or blocks the radio signals. So the simple idea is to pick up a stronger signal ans fed it via the cable inside the house and re radiate it to make the inside signal stronger. It is not amplifying the signal as such, but bringing it inside by cable and not having it lost in the walls.
A bit like having a light shining through a fiber optic pipe into a dark room.
It is an antenna to have outside in a higher signal area to pick up the signal from the tower. This signal will be greatly reduced inside as the building material absorbs or blocks the radio signals. So the simple idea is to pick up a stronger signal ans fed it via the cable inside the house and re radiate it to make the inside signal stronger. It is not amplifying the signal as such, but bringing it inside by cable and not having it lost in the walls.
A bit like having a light shining through a fiber optic pipe into a dark room.