The Invention of Radio

Portrait of Guglielmo Marconi. Credit: Public Domain

Radio owes its development to two other inventions: the telegraph and the telephone. All three technologies are closely related. Radio technology actually began as "wireless telegraphy."

The term "radio" can refer to either the electronic appliance that we listen with or the content playing from it. In any case, it all started with the discovery of "radio waves" or electromagnetic waves that have the capacity to transmit music, speech, pictures and other data invisibly through the air.

Many devices work by using electromagnetic waves including radio, microwaves, cordless phones, remote controlled toys, television broadcasts and more.

The Roots of Radio

During the 1860s, Scottish physicist James Clerk Maxwell predicted the existence of radio waves. And in 1886, German physicist Heinrich Rudolph Hertz demonstrated that rapid variations of electric current could be projected into space in the form of radio waves, similar to those of light and heat.

In 1866, Mahlon Loomis, an American dentist, successfully demonstrated "wireless telegraphy." Loomis was able to make a meter connected to one kite cause another one to move. This marked the first known instance of wireless aerial communication.

Guglielmo Marconi

Guglielmo Marconi, an Italian inventor, proved the feasibility of radio communication. He sent and received his first radio signal in Italy in 1895. By 1899, he flashed the first wireless signal across the English Channel and two years later received the letter "S," which was telegraphed from England to Newfoundland.

This was the first successful transatlantic radiotelegraph message in 1902.

Nikola Tesla

In addition to Marconi, two of his contemporaries, Nikola Tesla and Nathan Stufflefield, took out patents for wireless radio transmitters. Nikola Tesla is now credited with being the first person to patent radio technology.

The Supreme Court overturned Marconi's patent in 1943 in favor of Tesla.

Radiotelegraph and Spark-Gap Transmitters

Radio-telegraphy is the sending by radio waves the same dot-dash message (morse code) used in a telegraph. Transmitters at that time were called spark-gap machines. It was developed mainly for ship-to-shore and ship-to-ship communication. This was a way of communicating between two points. However, it was not public radio broadcasting as we know it today.

Wireless signals proved effective in communication for rescue work whenever a sea disaster occurred. A number of ocean liners even installed wireless equipment. In 1899, the United States Army established wireless communications with a lightship off Fire Island, New York. Two years later the Navy adopted a wireless system. Up until then, the Navy had been using visual signaling and homing pigeons for communication.

In 1901, radiotelegraph service was instituted between five Hawaiian Islands. By 1903, a Marconi station located in Wellfleet, Massachusetts carried an exchange or greetings between President Theodore Roosevelt and King Edward VII. In 1905, the naval battle of Port Arthur in the Russo-Japanese war was reported by wireless.

And in 1906, the U.S. Weather Bureau experimented with radiotelegraphy to speed up notice of weather conditions.

In 1909, Robert E. Peary, an arctic explorer, radiotelegraphed "I found the Pole." In 1910, Marconi opened regular American-European radiotelegraph service, which several months later enabled an escaped British murderer to be apprehended on the high seas. In 1912, the first transpacific radiotelegraph service linked San Francisco with Hawaii.

Improvements to Radio Transmitters

Overseas radiotelegraph service developed slowly, primarily because the initial radiotelegraph transmitter discharged electricity within the circuit and between the electrodes was unstable and caused a high amount of interference. The Alexanderson high-frequency alternator and the De Forest tube resolved many of these early technical problems.

Lee DeForest - AM Radio

Lee Deforest invented space telegraphy, the triode amplifier and the Audion. In the early 1900s, the big requirement for further development of radio was an efficient and delicate detector of electromagnetic radiation. De Forest provided that detector. It made it possible to amplify the radio frequency signal picked up by the antenna before application to the receiver detector. This meant that much weaker signals could be utilized than had previously been possible. De Forest was also the person who first used the word "radio."

The result of Lee DeForest's work was the invention of amplitude-modulated or AM radio that allowed for a multitude of radio stations. The earlier spark-gap transmitters did not allow for this.

Military Use and Patent Control

When the United States entered the first world war in 1917, all radio development was controlled by the U.S. Navy to prevent its possible use by enemy spies. The U.S. government took over control of all patents related to radio technology.

In 1919, after the government released its control of all patents, the Radio Corporation of America (RCA) was established with the purpose of distributing control of the radio patents that had been restricted during the war.

Radio Speaks

The first time the human voice was transmitted by radio is debateable. Claims to that distinction include the phrase, "Hello Rainey," which was spoken by Nathan B. Stubblefield to a test partner near Murray, Kentucky in 1892 as well as an experimental program of talk and music by Reginald A. Fessenden in 1906 that was heard by radio-equipped ships within several hundred miles.

Reginald A. Fessenden

Canadian Reginald A. Fessenden is best known for his invention of the modulation of radio waves and the fathometer. Fessenden worked as a chemist for Thomas Edison during the 1880s and later for Westinghouse. Fessenden started his own company, where he invented the modulation of radio waves known as the "heterodyne principle," which allowed the reception and transmission on the same aerial without interference.

True Broadcasting Begins

In 1915, speech was first transmitted across the continent from New York City to San Francisco and across the Atlantic Ocean, from Naval radio station NAA at Arlington, Virginia to the Eiffel Tower in Paris.

On November 2, 1920, Westinghouse's KDKA-Pittsburgh broadcasted the Harding-Cox election returns and began a daily schedule of radio programs.

The first ship-to-shore two way radio conversation occurred in 1922, between Deal Beach, New Jersey and the S.S. America, stationed 400 miles at sea. However, it was not until 1929 that high seas public radiotelephone service was inaugurated.

At that time, telephone contact could be made only with ships within 1,500 miles of shore. Today, there is the ability to telephone nearly every large ship wherever it may be on the globe.

In 1927, Commercial radiotelephony linking North America with Europe was opened. In 1935 the first telephone call was made around the world using a combination of wire and radio circuits.

FM Radio

Edwin Howard Armstrong invented frequency-modulated or FM radio in 1933. FM improved the audio signal of radio by controlling the noise static caused by electrical equipment and the earth's atmosphere. Until 1936, all American transatlantic telephone communication had to be routed through England. That year, a direct radiotelephone circuit was opened to Paris. Telephone connection by radio and cable is now accessible with 187 foreign points.

Radio technology has grown significantly since its early development. In 1947, Bell Labs scientists invented the transistor. In 1954, a then small Japanese company called Sony introduced the transistor radio.

FM Antenna System

In 1965, the first Master FM Antenna system in the world designed to allow individual FM stations to broadcast simultaneously from one source was erected on the Empire State Building in New York city.