Image: Heinrich Hertz discovering radio waves

Description: Artist's conception of German scientist Heinrich Hertz historic discovery of radio waves in 1886. To generate the waves Hertz used a spark gap radio transmitter consisting of a spark gap between two brass balls attached to a half-wave dipole antenna consisting of two wires with metal plates at the ends, powered by a Ruhmkorff coil with primary current supplied by a set of liquid batteries on the lower table. The Ruhmkorff coil generated pulses of high voltage which caused sparks to jump between the brass balls. Each spark excited oscillating radio frequency currents in the antenna, which were radiated as electromagnetic waves (radio waves). For a receiver, Hertz used a simple loop of wire (in his hands) with brass balls on the ends close together, forming a narrow spark gap. The length of the wire was a quarter wavelength, so the loop formed a resonant loop antenna, and the radio waves excited a voltage in the wire. So each spark of the transmitter excited a spark in the receiver loop.
Title: Heinrich Hertz discovering radio waves
Credit: Downloaded September 12, 2013 from Raymond Francis Yates, Louis Gerard Pacent (1922) The Complete Radio Book, The Century Co., New York, p. 32 on Google Books
Author: Unknown
Usage Terms: Public domain
License: Public domain
Attribution Required?: No