Radio waves are produced by controlled induction of movement of charges along a transmission antenna to produce a variable electric field that results in the propagation of an electromagnetic wave. An electromagnetic wave is sustained by the induction of magnetic fields by electrical fields and the reciprocal induction of electric fields by magnetic fields. These electromagnetic radio waves impact target antenna and cause corresponding changes in charge distribution along the receiving antenna that can be translated into sound.

The culmination of 19th century experimentation with electricity and magnetism was embodied in the equations of the electromagnetic field published by Scottish physicist James Clerk Maxwell. Maxwell's equations describing the propagation of electromagnetic waves predicted the existence of a spectrum of such waves that varied only in frequency and wavelength. In such an electromagnetic spectrum, visible light comprised but one region.

In 1888, German physicist Henrich Rudolph Hertz demonstrated the existence...