Longwave

The Longwave Broadcasting

Longwave broadcasting (LW BC) refers to the transmission of radio signals on frequencies ranging from 148.5 to 283.5 kHz. This form of broadcasting emerged in the early 20th century and played a crucial role in global communication, especially in Europe and parts of Asia.

The beginnings

Longwave broadcasting began in the 1920s, gaining traction as countries sought to establish national and international radio services. Unlike medium wave (AM) and shortwave broadcasts, LW BC provided stable and long-range coverage, making it ideal for reaching remote areas and maritime communication. Its ability to cover vast distances without interference made it an attractive option for government-run stations and public service broadcasters.

The peak era

LW BC reached its peak during the mid-20th century, particularly from the 1930s to the 1970s. European countries, including the UK, France, Germany, and Russia, heavily relied on longwave to broadcast national programs, news, and cultural content. Popular stations such as BBC Radio 4, France Inter, and Deutschlandfunk utilized longwave frequencies to reach audiences far beyond urban centers.

During the Cold War, longwave radio also played a strategic role, allowing governments to disseminate information across borders. The reliable nature of longwave signals, which could travel hundreds or even thousands of kilometers, ensured accessibility even in areas with challenging topography or political restrictions.

Propagation characteristics

Longwave signals propagate primarily through ground waves, which follow the curvature of the Earth, allowing for long-distance transmission with minimal attenuation. This makes longwave ideal for stable, consistent coverage over hundreds of kilometers, even in challenging weather conditions. Additionally, longwave signals can penetrate deep into buildings and underground structures, enhancing reception in areas where higher-frequency signals might struggle. At night, longwave propagation can be influenced by ionospheric reflections, though this effect is less pronounced compared to shortwave transmissions.

Decline and modern status

The decline of longwave broadcasting began in the late 20th century with the rise of FM radio, satellite broadcasting, and the internet. FM offered superior sound quality, while satellite and digital platforms provided more content variety and reliability. The transition to digital broadcasting (such as DAB and streaming services) led many countries to phase out LW BC in favor of modern alternatives.

Today, longwave broadcasting is a shadow of its former self. Many European broadcasters have shut down their LW transmitters, citing high operational costs and decreasing listener numbers. However, some stations, such as BBC Radio 4 (198 kHz) and a few others in Eastern Europe and Russia, continue to operate on longwave, primarily for legacy reasons or to serve specific audiences. Additionally, longwave remains relevant for certain niche applications, including emergency broadcasting and maritime navigation signals.

While longwave broadcasting may never return to its former prominence, it remains a fascinating chapter in the history of radio communication, reflecting the evolution of technology and changing listener habits over the decades.

List of old LW transmitter sites

The most important LW BC transmitter sites of the last century:

1. BBC Droitwich (UK) – Opened in 1934, this site was the primary longwave transmitter for BBC Radio 4 (198 kHz), providing national coverage and emergency broadcasts.
2. Allouis (France) – Built in the 1930s and later upgraded, this site transmitted France Inter on 162 kHz until 2016 and still broadcasts the TDF time signal.
3. Sasnovy (Belarus) – A key Soviet-era site, it operated on 252 kHz with high power for international broadcasts and remained in use for state radio.
4. Taldom (Russia) – One of the most powerful Soviet longwave stations, it broadcasted across the USSR and beyond, often carrying government and propaganda programming.
5. Donebach (Germany) – Operational from 1967 to 2015, this site transmitted Deutschlandfunk on 153 kHz, serving Germany and parts of Europe.
6. Lakihegy (Hungary) – Established in the 1920s, this site was home to a famous Blaw-Knox tower and transmitted Magyar Rádió, later transitioning to longwave at 540 m.
7. Kalundborg (Denmark) – Opened in 1927, it still transmits DR’s longwave service on 243 kHz, making it one of the few remaining active longwave stations.
8. Orfordness (UK) – Originally a military transmission site, it later carried BBC World Service and various experimental broadcasts before closing in 2012.
9. Grimeton (Sweden) – A UNESCO World Heritage site, this station, built in 1924, used an Alexanderson alternator for longwave telegraphy and still operates on special occasions.
10. Motala (Sweden) – One of Sweden’s most famous broadcast transmitters, it operated on 191 kHz and served as the main transmitter for Swedish Radio.
11. Ljungby (Sweden) – A major Swedish longwave transmitter site active on 278 kHz until it was shut down in 1978.
12. Burg (Germany) – A longwave station that transmitted on 261 kHz, used for East German radio and later decommissioned.
13. Clarkstown (Ireland) – Used by RTÉ Radio 1 on 252 kHz from 1989 until 2023, providing national and international coverage, including for Irish expatriates.
14. Zehlendorf (Germany) – A powerful longwave transmitter in Berlin used for German broadcasts and later for time signals.
15. Brasov (Romania) – A key longwave transmitter used for Romanian Radio on 153 kHz.
16. Moscow Taldom (Russia) – Another major Soviet longwave transmitter, used for high-power broadcasting across Eastern Europe and beyond.
17. Gafsa (Tunisia) – Used by Radio Tunis on 234 kHz, covering North Africa and parts of Europe.
18. Stara Zagora (Bulgaria) – The main longwave transmitter for Bulgarian National Radio on 261 kHz.

This list covers some of the most important longwave broadcast stations of the 20th and early 21st centuries, many of which have since been shut down or repurposed.