Beginnings of radio
There are varying disputed claims about who invented radio, which in the beginning was called "wireless telegraphy". The key invention for the beginning of "wireless transmission of data using the entire frequency spectrum", known as the spark-gap transmitter, has been attributed to various men. Marconi equipped ships with lifesaving wireless communications and established the first transatlantic radio service. Tesla developed means to reliably produce radio frequency electrical currents, publicly demonstrated the principles of radio, and transmitted long distance signals.
Nikola Tesla
In 1891 Tesla began his research into radio. In 1892 he gave a lecture in London. In 1893, in St. Louis, Missouri, Tesla gave a public demonstration of radio communication. Addressing the Franklin Institute and the National Electric Light Association, he described in detail the principles of radio communication.
The apparatus that Tesla used contained all the elements that were incorporated into radio systems before the development of the "oscillation valve", the early vacuum tube. Tesla initially used sensitive electromagnetic receivers,that were unlike the less responsive coherers later used by Marconi and other early experimenters.
Oliver Lodge
Oliver Lodge first transmitted radio signals on August 14, 1894 at a meeting at Oxford University. In August 1898 "Electric Telegraphy", made wireless signals using Tesla coils for the transmitter. This was key to the "syntonic" tuning concept. In 1912 Lodge sold the patent to Marconi.
Jagdish Chandra Bose
In November 1894, Jaqdish Bose, demonstrated publicly the use of radio waves in Calcutta. Bose ignited gunpowder and rang a bell at a distance using electromagnetic waves, proving that communication signals can be sent without using wires. He was thus the first to send and receive radio waves over a significant distance but did not commercially exploit this achievement.
Alexander Popov
In 1895, the Russian physicist Alexander Popov built a coherer. On May 7, 1895, Popov performed a public demonstration of transmission and reception of radio waves used for communication at the Russian Physical and Chemical Society. He did not apply for a patent for this invention. Popov's early experiments were transmissions of only 600 yards. Popov was the first to develop a practical communication system based on the coherer, and is usually considered by the Russians to have been the inventor of radio.
Around March 1896 Popov demonstrated in public the transmission of radio waves, between different campus buildings, to the Saint Petersburg Physical Society. Per other accounts, however, Popov achieved these results only in December 1897—that is, after publication of Marconi's patent. In 1898 his signal was received 6 miles away, and in 1899 30 miles away.
Ernest Rutherford
The New Zealander Earnest Rutherford was instrumental in the development of radio. In 1895 he was awarded an Exhibition of 1851 Science Research Scholarship to Cambridge. He arrived in England with a reputation as an innovator and inventor, and distinguished himself in several fields, initially by working out the electrical properties of solids and then using wireless waves as a method of signalling. Rutherford increased the sensitivity of his apparatus until he could detect electromagnetic waves over a distance of several hundred meters.
Julio Cervera Baviera
Recent studies in Spain credit Juilio Baviera as the inventor of the radio (in 1902). He began collaborating with Marconi on resolving the problem of a wireless communication system, obtaining some patents by the end of 1899. Cervera, who had worked with Marconi and his assistant George Kemp in 1899, resolved the difficulties of wireless telegraph On March 22, 1902, Cervera founded the Spanish Wireless Telegraph and Telephone Corporation and brought to his corporation the patents he had obtained in Spain, Belgium, Germany and England.Around 1900, Tesla opened the Tower facility and advertised services. In 1901, Marconi conducted the first successful transatlantic experimental radio communications. In 1903, Wardenclyffe Tower neared completion. Various theories exist on how Tesla intended to achieve the goals of this wireless system (reportedly, a 200 kW system). Tesla claimed that Wardenclyffe, as part of a World System of transmitters, would have allowed secure multichannel transceiving of information, universal navigation, time synchronization, and a global location system.
In 1904, The U.S. Patent Office reversed its decision, awarding Marconi a patent for the invention of radio, possibly influenced by Marconi's financial backers in the States. This also allowed the U.S. government (among others) to avoid having to pay the royalties that were being claimed by Tesla for use of his patents. In 1907, Marconi established the first commercial transatlantic radio communications service.
British Marconi
British Marconi was established in 1897 and began communication between coast radio stations and ships at sea. Many inventions improved the quality of radio, and amateurs experimented with uses of radio, thus the first seeds of broadcasting were planted.
Telefunken
The company Telefunken was founded on May 27, 1903 as "Telefunken society for wireless telefon" of Siemens & Halske in Berlin. It continued as a joint venture of AEG and Siemens AG, until Siemens left in 1941. In 1911, Kaiser Wilhelm ll sent Telefunken engineers to New York to erect three 600-foot (180-m) radio towers there. Nikola Tesla assisted in the construction. A similar station was erected in Nauen, creating the only wireless communication between North America and Europe.
Charles David Herrold
In April 1909 Charles Herrold, an electronics instructor in San Jose, California constructed a broadcasting station. It used spark gap technology, but modulated the carrier frequency with the human voice, and later music. The station "San Jose Calling" continued to today in. Herrold, the son of a Santa Clara Valley. farmer, coined the terms "narrowcasting" and "broadcasting", respectively to identify transmissions destined for a single receiver such as that on board a ship, and those transmissions destined for a general audience. Charles Herrold claimed to be the first to conduct "broadcasting".
Harold J. Power
On March 8, 1916, American Radio and Research Company (AMRAD), broadcast the first continuous broadcast in the world from Tufts University. The company later became the first to broadcast on a daily schedule, and the first to broadcast radio dance programs, university professor lectures, the weather, and bedtime stories.
Edwin Armstrong
Inventor Edwin Armstrong is credited with developing many of the features of radio as it is known today. Armstrong patented three important inventions that made today's radio possible.Regeneration, the superheterodyne circuit and wide-band frequency modulation or FM. Regeneration or the use of positive feedback greatly increased the amplitude of received radio signals to the point where they could be heard without headphones. The superhet simplified radio receivers by doing away with the need for several tuning controls. It made radios more sensitive and selective as well. FM gave listeners a static-free experience with better sound quality and fidelity than AM.