page_title: Medium wave
hierarchical_section_title: Medium wave
caption_attribution_description: English: A mast radiator antenna for an AM radio station transmitter in Chapel Hill, North Carolina. The radio frequency current from the transmitter is applied directly to the steel lattice tower, which acts as a monopole antenna element. The tower is supported at its base by a massive porcelain insulator, which insulates it from the ground. The high voltage on the tower can deliver a dangerous shock to anyone that touches it, so it is surrounded by a fence to keep people out. The white shed is called a helix house and contains an antenna tuner matching network to match the impedance of the antenna to the transmitter to allow power to be transferred efficiently to the antenna. The mast is supported by guy wires (faint), which have strain insulators in them to prevent the high voltage on the tower from being conducted to ground.
context_page_description: Medium wave is the part of the medium frequency radio band used mainly for AM radio broadcasting. The spectrum provides about 120 channels with limited sound quality. During daytime, only local stations can be received. Propagation in the night allows strong signals within a range of about 2000 km. This can cause massive interference because on most channels, about 20 to 50 transmitters operate simultaneously worldwide. In addition to that, amplitude modulation is prone to interference by all sorts of electronic devices, especially power supplies and computers. Strong transmitters cover larger areas than on the FM broadcast band but require more energy. Digital modes are possible but have not reached the momentum yet.
  MW was the main radio band for broadcasting from the beginnings in the 1920s into the 1950s until FM with a better sound quality took over. In Europe, digital radio is gaining popularity and offers AM stations the chance to switch over if no frequency in the FM band is available. Many countries in Europe have switched off their MW transmitters since the 2010s.
context_section_description: Medium wave (MW) is the part of the medium frequency (MF) radio band used mainly for AM radio broadcasting. The spectrum provides about 120 channels with limited sound quality. During daytime, only local stations can be received. Propagation in the night allows strong signals within a range of about 2000 km. This can cause massive interference because on most channels, about 20 to 50 transmitters operate simultaneously worldwide. In addition to that, amplitude modulation (AM) is prone to interference by all sorts of electronic devices, especially power supplies and computers. Strong transmitters cover larger areas than on the FM broadcast band but require more energy. Digital modes are possible but have not reached the momentum yet.
  MW was the main radio band for broadcasting from the beginnings in the 1920s into the 1950s until FM with a better sound quality took over. In Europe, digital radio is gaining popularity and offers AM stations the chance to switch over if no frequency in the FM band is available. Many countries in Europe have switched off their MW transmitters since the 2010s.
  The term is a historic one, dating from the early 20th century, when the radio spectrum was divided on the basis of the wavelength of the waves into long wave (LW), medium wave, and short wave (SW) radio bands.
caption: Typical mast radiator of a commercial medium wave AM broadcasting station, Chapel Hill, North Carolina, U.S.
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