Radio waves know no borders. From the very beginning Radiojournal's "domestic" broadcasts could also be received abroad, and foreign stations could be picked up in Czechoslovakia. And reception was also easier, because the spectrum of radio frequencies was not yet crowded with hundreds of stations as it is today. Special programmes - lectures in Esperanto - were soon created, tailored for a foreign audience. The first was broadcast in January 1924, and the lectures were informative: important events held in Prague, important anniversaries and so on.
At the end of 1925 a new broadcasting station in Prague-Stranice was opened, built by General Electric. Its output of 5kW made it one of the most powerful radio transmitters in Europe at the time. Radiojournal used the transmitter for experimental long-distance broadcasts. Letters sent by listeners confirmed that concerts broadcast on medium wave from the Strasnice transmitter were picked up as far away as North America.
1926 saw the first broadcasts of foreign language lectures about Czechoslovakia. These were initially in English and French, later followed by German, and concerned more contemporary issues than the Esperanto programmes. The lectures followed Thursday evening's regular "domestic" broadcasts and were intended for listeners in Europe. The mid-1920s also saw the creation of a programme for Czechoslovak expatriates, broadcast on Wednesday evenings.
Shortwave broadcasting was still in its infancy. All radio traffic and broadcasting of that time was conducted on wavelengths that were longer than 200 metres, i.e on the medium and long-wave bands of today. The "200 metres and under" or "shortwave" band was allocated to amateur radio enthusiasts for experimental transmissions. Their experiments quickly bore fruit. 1923 saw the first successful transatlantic contact between the U.S. and France on frequencies in the 110m band. Experiments suggested that shorter wavelengths could be even more suitable for long-distance transmissions. Broadcasters soon picked up on this fact, and began using shortwave as well. It was theDutch firm Phillips which made history. In 1927 the company began broadcasting on shortwave from a transmitter in Eindhoven. In 1928 the station, which used the callsign 'PCJ', began broadcasting a multi-lingual programme called "Happy Station".
The importance of international broadcasting grew significantly in the 1930s. Radio quickly became an effective propaganda tool, and both the fascist and anti-fascist European powers relied heavily on the medium. The United Kingdom and Italy began broadcasting to their colonies in 1932. Germany began broadcasting to Austria, the Sudetenland and Latin America in 1933, and in the mid-1930s Soviet radio launched its own international service. Czechoslovakia monitored these broadcasts closely. In 1929 the Radio Monitoring Service was established, working under the Ministry of Post and Telegraphs