The first successful radio transmission had been…
1887 CE
The first successful radio transmission had been made by David Edward Hughes in 1879, but it is not conclusively proven to be electromagnetic waves until the experiments of Heinrich Hertz in 1886.
For the Hertz radio wave transmitter, he uses a high voltage induction coil, a condenser (capacitor, Leyden jar) and a spark gap—whose poles on either side are formed by spheres of two centimeter radius—to cause a spark discharge between the spark gap’s poles oscillating at a frequency determined by the values of the capacitor and the induction coil.
To prove there really is radiation emitted, it has to be detected.
Hertz uses a piece of copper wire, one millimeter thick, bent into a circle of a diameter of seven point five centimeters, with a small brass sphere on one end, and the other end of the wire is pointed, with the point near the sphere.
He buys a screw mechanism so that the point can be moved very close to the sphere in a controlled fashion.
This "receiver" is designed so that current oscillating back and forth in the wire will have a natural period close to that of the "transmitter" described above.
The presence of oscillating charge in the receiver will be signaled by sparks across the (tiny) gap between the point and the sphere (typically, this gap is hundredths of a millimeter).
In more advanced experiments in 1887, Hertz measures the velocity of electromagnetic radiation and finds it to be the same as the light’s velocity.
He also shows that the nature of radio waves’ reflection and refraction is the same as those of light and establishes beyond any doubt that light is a form of electromagnetic radiation obeying the Maxwell equations, thus ending arguments in the field of electrodynamics about action at a distance.
Heirich Hertz was born in Hamburg, then a sovereign state of the German Confederation, into a prosperous and cultured Hanseatic family.
His father, David Gustav Hertz, was a writer and later a senator.
His mother was the former Anna Elisabeth Pfefferkorn.
His paternal great-grandfather, David Wolff Hertz (1757–1822), fourth son of Benjamin Wolff Hertz, moved to Hamburg in 1793, where he made his living as a jeweler; he and his wife Schöne Hertz (1760–1834) were buried in the former Jewish cemetery in Ottensen.
Their first son, Wolff Hertz (1790–1859), was chairman of the Jewish community.
Hertz' paternal grandfather, Heinrich David Hertz (1797–1862), was a respected businessman, and his paternal grandmother, Betty Oppenheim, was the daughter of the banker Salomon Oppenheim, from Cologne.
Hertz's father and paternal grandparents converted from Judaism to Christianity.
His mother's family was Lutheran.
While studying at the Gelehrtenschule des Johanneums in Hamburg, he had shown an aptitude for sciences as well as languages, learning Arabic and Sanskrit.
He had studied sciences and engineering in the German cities of Dresden, Munich and Berlin, where he had studied under Gustav R. Kirchhoff and Hermann von Helmholtz.
Hertz had obtained his PhD from the University of Berlin in 1886 and remained for post-doctoral study under Helmholtz.
In 1883, he had taken a post as a lecturer in theoretical physics at the University of Kiel.
Hertz had become a full professor at the University of Karlsruhe in 1885.
The most dramatic prediction of Robert Clerk Maxwell's theory of electromagnetism, published in 1865, had been the existence of electromagnetic waves moving at the speed of light, and the conclusion that light itself was just such a wave.
This has challenged experimenters to generate and detect electromagnetic radiation using some form of electrical apparatus.