History of Radio
The word "radio" comes from the Latin word "radius" meaning "spoke of a wheel, beam of light, ray". It was first used for Alexander Graham Bell’s 1881 optical transmission system. Radios convert AM or FM radio signals back into the sounds they were made from. This reverse process is called demodulation. Radio wave emission is regulated and frequency bands allocated by the International Telecommunication Union (ITU).
Development and Popularity
In 1895, Gugliemo Marconi invented "the wireless telegraph" using radio waves to transmit Morse code. This instrument became known as the radio. Radios became widely popular in the early 1900s. By 1910 over a million were in use in the United States. The original use of radio was by the US military in World War I. Radio technology proved unreliable then but was still used for emergency battlefield communication when telephone and telegraph wires were cut.
Key Milestones
Radio waves are located at the low-frequency end of the electromagnetic spectrum, below other types of radiation. James Clerk Maxwell demonstrated in 1864 that electromagnetic waves could spread freely through space. In 1880 Heinrich Rudolf Hertz conclusively proved the existence of airborne electromagnetic waves, confirming Maxwell’s theory. The term “radio” was universally adopted 20 years later to describe electromagnetic radiation. By 1920 crystal radio sets were gradually replaced by vacuum tube radios. In the late 1920s and early 1930s, radio popularity grew rapidly. By 1934, 60% of US households had a radio.
Naming and Significance
How did radio get its name? The device we call a radio took its name from radio telegraphy. It was commonly referred to as “wireless” up until World War II when the military preference for radio caused that name to catch on to describe the revolutionary receptacle of sound. The word radio is derived from radius, Latin for “spoke of a wheel” or “ray of light,” because transmitted sounds travel out in all directions from a center hub like the spokes of a wheel.