Radio is a technology to broadcast mass media, which is already used since the early 20th century. Followed by television a few years later, both technologies are comparable regarding their transmission. The signal can be transmitted either by antenna, satellite or cable. For a transmission by antenna the signal is transferred to broadcasting stations and then broadcasted with terrestrial frequencies. For transmission by satellite parabolic antennas (dish aerials) are used to receive the signal which is forwarded by satellite. The signal can be received by cable or internet, too.