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History and invention
Main article: History of radio
The identity of the original inventor of radio, at the time called wireless telegraphy, is contentious. The controversy over who invented the radio, with the benefit of hindsight, can be broken down as follows:

Q1: Who invented 'wireless transmission of data using the entire frequency spectrum' (spark-gap radio)?
A1: Nikola Tesla, Guglielmo Marconi, and Alexander Popov (possibly in that order).
Q2: Who invented amplitude-modulated (AM) radio, so that more than one station can send signals (as opposed to spark-gap radio, where one transmitter covers the entire bandwidth of the spectrum)?
A2: Reginald Fessenden [1] and Lee de Forest.
Q3: Who invented frequency-modulated (FM) radio, so that an audio signal can avoid "static," that is, interference from electrical equipment and atmospherics?
A3: Edwin H. Armstrong and Lee de Forest.
Early radios ran the entire power of the transmitter through a carbon microphone. While some early radios used some type of amplification through electric current or battery, through the mid 1920s the most common type of receiver was the crystal set. In the 1920s, amplifying vacuum tubes revolutionized both radio receivers and transmitters.

Discovery and development
The theoretical basis of the propagation of electromagnetic waves was first described in 1873 by James Clerk Maxwell in his paper to the Royal Society A dynamical theory of the electromagnetic field, which followed his work between 1861 and 1865. In 1878 David E. Hughes was the first to transmit and receive radio waves when he noticed that his induction balance caused noise in the receiver of his homemade telephone. He demonstrated his discovery to the Royal Society in 1880 but was told it was merely induction. It was Heinrich Rudolf Hertz who, between 1886 and 1888, first validated Maxwell's theory through experiment, demonstrating that radio radiation had all the properties of waves (now called Hertzian waves), and discovering that the electromagnetic equations could be reformulated into a partial differential equation called the wave equation.

William Henry Ward was issued U.S. Patent 126356 on April 30, 1872. Mahlon Loomis was issued U.S. Patent 129971 on July 30, 1872. Landell de Moura, a Brazilian priest and scientist, conducted experiments after 1893 (but at least by 1894). He did not publicize his achievement until 1900. Claims have been made that Nathan Stubblefield invented radio before either Tesla or Marconi, but his device seems to have worked by induction transmission rather than radio transmission.

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