May 7 is Radio Day in Russia, Communications Workers’ Day (as it is officially known in Russia) or Radio and Television Day (Ден на радиото и телевизията, as it is known in Bulgaria,) in commemoration of the day in 1895 when Alexander Popov successfully demonstrated his invention.
Popov shares the title of Inventor of Radio along with Guglielmo Marconi who was making very similar discoveries in virtually the same period of time.
Actually, radio was the culmination of work from scientists around the world. Popov used Englishman Sir Oliver Lodge’s coherer in his demonstration, which was based on the findings of Frenchman Edouard Branly. The Italian Marconi, for his part, built upon the concept of radio waves discovered by the German physicist Heinrich Hertz.

Branly’s electrical circuit tube filled with iron filings(later called a “coherer”.)
Retrieved 6 February 2010 from Archie Frederick Collins 1905 Wireless Telegraphy: It’s History, Theory, and Practice, McGraw Publishing Co., New York, p. 146, fig. 133 on Google Books, Public Domain, https://commons.wikimedia.org/w/index.php?curid=29579053