This nice souvenir sheet on the cover was issued in 2009 to commemorate the 150th birth of Alexander Stepanovich Popov.
Popov (1859 – 1906) was a Russian physicist who first demonstrated the practical application of electromagnetic (radio) waves, although he did not apply for a patent for his invention.
Beginning in the early 1890s he continued the experiments of other radio pioneers, such as Heinrich Hertz. In 1894 he built his first radio receiver, a version of the coherer. Further refined as a lightning detector, it was presented to the Russian Physical and Chemical Society on May 7, 1895—the day has been celebrated in the Russian Federation as "Radio Day". The paper on his findings was published the same year. In March 1896, he effected transmission of radio waves between different campus buildings in St Petersburg. Upon learning about Guglielmo Marconi's system, he effected ship-to-shore communication over a distance of 6 miles in 1898 and 30 miles in 1899.
Beginning in the early 1890s he continued the experiments of other radio pioneers, such as Heinrich Hertz. In 1894 he built his first radio receiver, a version of the coherer. Further refined as a lightning detector, it was presented to the Russian Physical and Chemical Society on May 7, 1895—the day has been celebrated in the Russian Federation as "Radio Day". The paper on his findings was published the same year. In March 1896, he effected transmission of radio waves between different campus buildings in St Petersburg. Upon learning about Guglielmo Marconi's system, he effected ship-to-shore communication over a distance of 6 miles in 1898 and 30 miles in 1899.
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