A TV satellite dish is a passive device, that is, it does not emit any energy. The dish is a receiving device to capture signals from the satellite. Therefore there is no concern of radiofrequency exposure. However, because of the very weak signal from the satellite in space, it is important that there is no signal attenuation due to building materials. If you put it inside your apartment, the signal can be too weak and you may not get good reception, hence sattelite dishes being put on the roof.