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James Clerk Maxwell formulates the mathematical model of electromagnetism (classical electro-dynamics), “A Treatise on Electricity and Magnetism”, 1873. He shows that light is an electromagnetic (EM) wave, and that all EM waves propagate through space with the same speed, the speed of light.
Heinrich Rudolph Hertz demonstrates in 1886 the first wireless EM wave system: a λ /2 -dipole is excited with a spark; it radiates predominantly at λ≈ 8 m; a spark appears in the gap of a receiving loop some 20 m away. In 1890, he publishes his memoirs on electrodynamics, replacing all potentials by field strengths
In 1892, Tesla delivers a presentation at London about “transmitting intelligence without wires,” and, in 1895, he transmits signals detected 80 km away. His patent on wireless links precedes that of Marconi
May 7, 1895, a telegraph communication link is demonstrated by the Russian scientist, Alexander Popov. A message is sent from a Russian Navy ship 30 miles out in sea, all the way to his lab in St. Petersburg, Russia. This accomplishment is little known today.
Guglielmo Marconi sends signals over large distances and successfully commercializes wireless communication systems. In 1901, he performs the first transatlantic transmission from Poldhu in Cornwall, England, to Newfoundland, Canada. He receives the Nobel prize for his work in 1909.
The beginning of 20th century (until WW2) marks the boom in wire-antenna technology (dipoles and loops) and in wireless technology as a whole, which is largely due to the invention of the DeForest triode tube, used as radio-frequency (RF) generator. Radio links are realized up to UHF (about 500 MHz) and over thousands of kilometers.
WW2 marks a new era in wireless communications and antenna technology. The invention of new microwave generators (magnetron and klystron) leads to the development of the microwave antennas such as waveguide apertures, horns, reflectors, etc.
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