Journey of the Radio.
Radio is a culmination of two technologies - the telegraph and the telephone. To begin with, the telegraph worked with fixed wires and human intervention. In 1860’s James Clerk Maxwell predicted that radio waves existed and electromagnetic waves can be manipulated to transmit sound. By this time, the concept of wireless telegraphy had emerged. Mahlon Loomis - a dentist, and the famous inventor Thomas Edison both received patents for a wireless telegraph system. Coherer, a device that is used for receiving wireless signals, was invented by Temistocle Calzecchi-Onesti and further refined by Edouard Branly in 1886.
Heinrich Hertz, whose main area of work was electromagnetic waves, was able to transmit and receive wireless signals. In the year 1933, ‘Hertz’ the unit of measure of radio and electrical frequencies was named after him by the International System of Units (SI)
Nikola Tesla’s contributions towards the invention of the radio have been significant. In the year 1892, he successfully received and transmitted radio signals. In spite of set backs, he was able to launch a radio controlled boat in 1898. Around this time, he applied for a patent for the radio.
Guglielmo Marconi’s journey with the radio started when he was able to transmit wireless signals over a one and a half mile distance, while experimenting from the family’s estate. In 1895, he succeeded in using electromagnetic airwaves to send telegraphic signals. In 1896, he moved to England with his equipment and was introduced to Sir William Preece, who was the Engineer in Chief of the Post Office. Marconi’s real success lay in the fact his invention was commercially available. The equipment was being installed on ships. The fact that he was well connected in the British nobility enabled him to get a patent for the radio even though one existed in the name of Tesla. Because of this patent, a legal battle between the two started in the year 1915 and continued till 1943, with the U.S. Supreme Court confirming Tesla as the inventor of radio. This was much after Tesla's death. The Marconi Company was suing the United States Government for having used their patents in World War I. To avoid further complications. Tesla's patent was restored back to him.
Reginald Fessenden, an American, was responsible for the AM (Amplitude Modulation) radio. He had heard about Marconi’s invention and strongly believed that this technology could be more efficient and versatile. It could be used for audio broadcasts. By 1900 he was able to demonstrate his technology, which afterwards was to be used by the weather department for sending information to sailing ships. In 1910 Reginald conducted a test transmission, wherein, Enrico Caruso’s performance at the Metropolitan Opera House was broadcast over a distance of 20 miles to a merchant cargo ship. The New York Times of January 14, 1910 carried the news of this successful transmission.
The foundation of commercial broadcasting was laid with the broadcast of the Harding/Cox election. The broadcast was made using a station owned by Westinghouse. In between the commentary, other short programs were also broadcast. By 1920 the modern radio had arrived. Initially these devices were big and mounted in a cabinet.
Edwin Armstrong, continued with his experiments and reinvented radio broadcasting. His experiments led to FM (Frequency Modulation) radio. The FM equipment was costly.
The scene changed with the arrival of the transistor, which was invented by scientists from Bell Labs in the year 1947. It took another ten years, before a commercial model could be made available. Sony launched TR-63 a portable battery powered radio in 1957. At that time, it was the world’s smallest radio. The television was invented in the year 1926, and the first trans Atlantic (from London to Glasgow) television broadcast was made in the year 1928. In 1941, 10 stations received licenses to broadcast television programs but until around 1960’s the television began to dominate the world of electronic entertainment.
The radio is not the result of a single experiment but a series of experiments and inventions that finally culminated as the radio. The credit for this work goes to many innovative minds. An interesting trip through the history of the radio can be undertaken with the help of photographs available at http://oak.cats.ohiou.edu/~postr/MRT/Tour1.htm