MW AM Band

The Medium Wave Broadcasting

Medium Wave (MW) broadcasting, often referred to as AM (Amplitude Modulation) broadcasting, has played a crucial role in global communication for over a century. From its early days as a groundbreaking medium to its peak popularity and eventual decline in the digital era, MW broadcasting has undergone significant transformations.

9R-59 receiving AM broadcast

The beginnings of medium wave broadcasting

The origins of MW broadcasting date back to the early 20th century. In the 1920s, commercial AM radio stations began appearing worldwide, providing news, music, and entertainment to a growing audience. The simplicity and cost-effectiveness of AM transmission technology made it the standard for radio broadcasting. By the 1930s and 1940s, MW radio was the dominant medium for mass communication, serving both urban and remote areas.

Peak popularity and influence

The golden age of MW broadcasting spanned from the 1930s to the 1970s. During this period, major radio networks and independent stations flourished, delivering everything from live music performances and dramas to news and talk shows. MW broadcasting played a key role during World War II, allowing governments to disseminate information and propaganda. In the post-war years, it remained a primary source of news and entertainment, particularly in Europe, North America, and Asia.

At its height, AM radio had enormous reach, with powerful transmitters capable of covering vast distances. Some MW stations operated at up to 500 kW power, allowing them to be heard across entire continents, especially at night when skywave propagation enhanced signal reach.

Propagation characteristics of medium wave

MW broadcasting operates between 530 kHz and 1700 kHz (at least in the US) or 522 kHz to 1620 kHz (eg. Europe). One of its defining characteristics is its propagation behavior, which varies based on time of day and atmospheric conditions:

  • Ground Wave Propagation: During daylight hours, MW signals travel via ground waves, following the Earth’s surface. This limits their effective range to a few hundred kilometers, depending on terrain and soil conductivity.
  • Skywave Propagation: At night, MW signals can reflect off the ionosphere, significantly increasing their range. This phenomenon allows MW stations to be received thousands of kilometers away, making it a valuable tool for international broadcasting.

The decline of medium wave broadcasting

The decline of MW broadcasting began in the late 20th century, largely due to technological advancements and changing listener preferences. The rise of FM radio in the 1970s and 1980s, with its superior sound quality and resistance to interference, drew audiences away from AM stations. Later, the emergence of digital broadcasting, internet radio, and satellite services further eroded MW listenership.

Many countries have decommissioned their high-power AM stations, shifting focus to FM, DAB (Digital Audio Broadcasting), and online streaming. However, MW broadcasting remains in use for talk radio, emergency broadcasts, and rural communication in some regions.

Icom IC-7600 receiving 1458kHz

The status of medium wave today

Today, MW broadcasting is in decline but not entirely obsolete. Some countries, such as the United States, India, China, and parts of Africa, still operate AM stations due to their ability to cover large areas cost-effectively. In the U.S., MW remains popular for talk radio and news stations. India continues to use AM for national and regional broadcasts, especially in rural areas. China operates several high-power MW stations, providing state-run news and programming. In Africa, countries such as Nigeria and Egypt maintain MW services to reach audiences where FM and digital services are less accessible.

Despite its decreasing prominence, MW broadcasting continues to hold historical significance and a niche role in areas where other communication technologies are impractical. While its golden age has passed, MW radio remains a testament to the enduring power of broadcast media in shaping global communication.

List of old MW transmitter sites

The most important MW(AM) BC transmitter sites of the last century:

  1. WBBM Chicago (USA, 780 kHz) – One of the most powerful AM stations in the U.S., it has provided news and talk programming since the 1920s.
  2. WLW Cincinnati (USA, 700 kHz) – Famous for briefly running at 500 kW in the 1930s, earning it the nickname “The Nation’s Station.”
  3. KDKA Pittsburgh (USA, 1020 kHz) – Considered the world’s first commercial radio station, launching in 1920 with the Harding-Cox election results.
  4. XEW Mexico City (Mexico, 900 kHz) – One of Latin America’s most powerful AM stations, known as “La Voz de América Latina desde México.”
  5. XERA/XERF Ciudad Acuña (Mexico, 1570 kHz) – A legendary border blaster that transmitted at extreme power levels, made famous by Wolfman Jack.
  6. Radio Luxembourg (Luxembourg, 208 meters / 1440 kHz) – One of Europe’s most influential commercial broadcasters, reaching millions across the continent.
  7. BBC 5 Live Droitwich (UK, 693 & 909 kHz) – The main AM transmitter for BBC 5 Live, covering news and sports across the UK.
  8. Orfordness (UK, 648 kHz) – Formerly home to BBC World Service, it was one of the most powerful AM stations in Europe.
  9. Mühlacker (Germany, 576 kHz) – One of Germany’s oldest AM sites, operational since 1930, with a famous 273-meter antenna mast.
  10. Monte Ceneri (Switzerland, 558 kHz) – The main Italian-language AM transmitter for Switzerland, serving listeners for decades.
  11. Madrid Arganda del Rey (Spain, 585 kHz) – A key Spanish AM station used by Radio Nacional de España for national coverage.
  12. Moscow (Russia, 720 & 873 kHz) – Soviet-era high-power mediumwave transmitters that carried Radio Moscow’s international broadcasts.
  13. Kaunas Sitkūnai (Lithuania, 1386 kHz) – A Cold War-era station that played a key role in relaying Western broadcasts into the Soviet Union.
  14. Brasov Bod (Romania, 1152 kHz) – One of Eastern Europe’s major AM sites, used for powerful transmissions of Radio Romania.
  15. Marrakech (Morocco, 540 kHz) – A high-power AM site covering North Africa and Southern Europe.
  16. Delhi Kingsway (India, 819 kHz) – A historic mediumwave transmitter used by All India Radio to reach vast audiences.
  17. Shanghai (China, 990 kHz) – One of China’s most significant AM broadcast sites, serving the country’s massive radio audience.
  18. Sydney 2UE (Australia, 954 kHz) – One of Australia’s longest-running commercial AM stations, influential in news and talk radio.

Many of these stations played crucial roles in national and international broadcasting. Some still operate, while others have been shut down due to the decline of AM radio.