In 1929 the Brussels frequency plan takes effect: the separation between stations are now 9 kHz up to 1000 kHz and 10 kHz above 1000 kHz.
A few months later the Prague frequency plan takes effect: the 9 kHz separation is extended to stations up to 1400 kHz, 10 kHz separation remains above 1400 kHz.

The European frequency conference in Montreux of April 1939 draws up a new frequency plan for long and medium wave to become active on 4 March 1940. Large broadcasters can transmit with powers up to 120 kW on medium wave, and 500 kW during the day and 200 kW during the night on long wave. 32 of the 37 present countries sign the new plan. Iceland, Greece, Luxembourg, Turkey and the USSR did not agree.

On 22 January 1965 a treaty is signed in Strasbourg to prevent radio and television transmissions outside the national territory. This way measures can be taken against the many offshore stations. Nothing is done against stations such as Vatican Radio, Radio Moscow and Radio Luxembourg, who transmit with a much higher power than admitted.

On 6 February 1988 a new longwave plan comes into effect: all stations between 198 and 234 kHz go 2 kHz lower.

see also:
list of European stations in 1925
list of European stations in 1937