Radio Day is marked on May 7
Radio Day takes place on 7 May, the day in 1895 on which Alexander Popov successfully demonstrated his invention.
In 1895, Popov gave the first public demonstration of radio as a tool before the Russian Physical and Chemical Society in St. Petersburg, using Sir Oliver Lodge's coherer as a lightning detector.
Popov has generally been recognized in Eastern Europe as an "inventor of radio," in contrast to the West's recognition of Guglielmo Marconi as the first to develop a viable system based on radio (Herzian) waves.
Radio Day was first observed in the Soviet Union in 1945, on the 50th anniversary of Popov's experiment, and some four decades after his death. Radio Day is officially marked in Russia and Bulgaria.