Satellite Communications - Microwaves can penetrate the atmosphere of the earth. This is the reason why they are used for satellite communications. Communication satellites travel around the earth at an altitude of 35,000 km above the equator. They move at a speed of 11 300 km/h and revolve around the earth every 24 hours, the same rate as the rotation of the earth. This makes them appear to be stationary when seen on Earth. Antennae are mounted to point in fixed directions towards these satellites. Microwaves signals are transmitted by an antenna to a satellite which amplifies and re-transmits the signal to an antenna in other parts of the world. This is how we communicate with the rest of the world,​