Radio

On 24 December 1906, the first radio broadcast for entertainment and music was transmitted from Brant Rock, Massachusetts to the general public. This pioneering broadcast was achieved after years of development work by Reginald Aubrey Fessenden (1866-1932) who built a complete system of wireless transmission and reception using amplitude modulation (AM) of continuous electromagnetic waves. This technology was a revolutionary departure from transmission of dots and dashes widespread at the time.

On the morning of 17 April 1967, radio astronomers used this radiotelescope at DRAO and a second one at the Algonquin Radio Observatory located 3074 km away to make the first successful radio astronomical observations using Very Long Baseline Interferometry. Today, VLBI networks span the globe, extend into space and continue to make significant contributions to both radio astronomy and geodesy.

The first use of wireless telegraphy in the field occurred during the Anglo-Boer War (1899-1902). The British Army experimented with Marconi's system and the British Navy successfully used it for communication among naval vessels in Delagoa Bay, prompting further development of Marconi's wireless telegraph system for practical uses. The Anglo-Boer War of 1899-1902 will be remembered as the last of the gentleman's wars, the war that marked the end of the Victorian era.

The discovery of the radioconduction is a phenomenon which revolutionized the means of communication. It is at the origin of the development of the TSF (Télégraphie Sans Fil, or wireless telegraphy). As a member of the French Academy of Sciences (it gains vis-a-vis Marie Curie), Branly received international recognition. No more than about fifteen years separate the first wireless transmission across a few meters (1890) from the first transatlantic communication (Marconi, December 1901).

Beginning in 1924, Professor Hidetsugu Yagi and his assistant, Shintaro Uda, designed and constructed a sensitive and highly-directional antenna using closely-coupled parasitic elements. The antenna, which is effective in the higher-frequency ranges, has been important for radar, television, and amateur radio. The antenna system, using a driven element with closely coupled parasitics (usually a reflector and one or more directors) for short-wave work, was first described by S. Uda, a professor at Tohuku University in Japan, in 1926, in the IEEJ (Japan). A colleague, Professor H.

Dr. Takeshi Takei, the professor at the Tokyo Institute of Technology, discovered that composite oxides containing zinc and iron have distinguished magnetic properties. In 1930, Prof. Takei submitted a paper on his work to Japanese Electro-chemical Society and also presented a paper at 57th General Meeting of American Electrochemical Society in St. Louis. That same year, Prof. Takei applied a patent for his discovery, which was granted in 1932(Japan PAT-98844). Tokyo Denki Kagaku Kogyo (now TDK Corporation) was founded in 1935 to commercialize this newly invented ferrite cores.

"The Alexanderson radio alternator was a high-power, radio-frequency source which provided reliable transoceanic radiotelegraph communication during and after World War I. Ernst F.W. Alexanderson (1878-1975), a General Electric engineer, designed radio alternators with a frequency range to 100 kHz and a power capability from 2 kW to 200 kW.