The History of Radio
The word radio has different meanings to different people, mostly depending on a person's age. When mentioning radio in 2008, younger people may think of it as not only the traditional radio that comes in most cars, but also satellite radio and Internet radio stations. The topic of discussion here is going to be the history of traditional radio, or also known as terrestrial radio.
Radio has it's roots in the telegraph, invented by Guglielmo Marconi and patented in 1896 in England. Marconi's telegraph, sending transatlantic messages in Morse code, quickly became a commercial success and the dominant means of wireless marine communication at the beginning of the 20th century.
Discoveries in electricity were crucial in the development of radio. Working from Thomas Edison's discovery that electrons were emitted from a heated element, John Ambrose Fleming inserted a positively charged plate into the filament, allowing a change from alternating to direct current. The "Fleming valve" would be the precursor to Lee de Forest's Audion, in which he inserted a grid onto the plate to allow the tube to function as an amplifier for receiving signals.
Around 1914, Edwin Howard Armstrong was working on a way to use the Audion as both a transmitter and a receiver. "Within a few months of each other in 1914, de Forest and Armstrong individually applied for patents on what became known as the regenerative or feedback circuit. One of the longest and most bitter fights in radio history resulted from this conflict over patent priority, leading in 1928 and again in 1934 to the United States Supreme Court. Although the engineering community generally believed that Armstrong had a sounder grasp of the principles behind the circuit than de Forest had, the court held in favor of de Forest. Today, engineering texts and organizations generally give Armstrong credit for this crucial invention, but the law gave it to de Forest" (Sterling and Kittross, p. 37-38). This was to become what is now known as amplitude modulation, or AM, radio.
In 1978, Rock and Roll Hall of Fame inductees and Grammy Award winners Walter Becker and Donald Fagen, known collectively as Steely Dan, wrote and recorded the title track for the movie F.M. In the song, they sing "FM - no static at all." Edwin Armstrong set about experimenting with ways to eliminate static.
One of the most influential men in the history of broadcasting is David Sarnoff. Born in Russia, Sarnoff eventually made his way to America and became an operator for the Marconi Wireless Telegraph Company as a teenager. Sarnoff eventually became president of RCA. Armstrong and Sarnoff had a long history with the evolution of AM. While Sarnoff was thoroughly impressed with Armstrong's discovery, he wasn't interested in spending the money to develop a new system that would replace AM and had his own ideas of developing a new concept called television. Armstrong was successful in getting governmental approval of commercial FM stations, but growth and availability of receivers capable of receiving the signal was slow.
Between 1945 and 1952, America saw a boom in FM stations, going from 46 stations to 629 stations on the air. By 1960, there were nearly 750 FM stations in operation and applications continued to skyrocket. AM continued to have a strong hold on the market throughout the 1970s as the concept of the car stereo was introduced, but as an after-market upgrade to installed AM receivers in older automobiles. Changes in musical tastes of a younger generation flocked to FM in the early 1980s that gave a new generation its own identity.
AM and FM radio are still around and are still commercially viable. But, since you are on this page, you are probably investigating what the future holds for radio.
Sterling, C. H., & Kittross, J. M. (2002). Stay tuned: a history of American broadcasting (3rd ed.) Mahwah: Lawrence Erlbaum Associates.