The louder you shout, the easier it is to hear someone at a distance. Louder noises make bigger sound waves that have the power to travel further before they get soaked up by bushes, trees, and all the clutter around us. The same is true of radio waves. To make radio waves that are strong enough to carry radio and TV pictures many miles from a TV station to someone's home, you need a really powerful transmitter. This is effectively a giant antenna (aerial), often positioned on top of a hill so it can send signals as far as possible.