For a broader coverage related to this topic, see History of radio. Many people were involved in the invention of radio as we know it today. Maxwell published A Treatise on Electricity and Magnetism in bose wave radio iii manual pdf, stimulating many people to experiment with wireless communication. Others experimented without the benefit of his theories.
After Hertz’s work many people were involved in further development of the electronic components and methods to improve the transmission and detection of electromagnetic waves. Around the turn of the 20th century, Guglielmo Marconi developed the first apparatus for long distance radio communication. By 1910 these various wireless systems had come to be referred to by the common name “radio”. Before the discovery of electromagnetic waves and the development of radio communication there were many wireless telegraph systems proposed or tried out. Early researchers may not have understood or disclosed which physical effects were responsible for transmitting signals.
These experimenters used the existing theories of the day or novel theories of their own on how wireless signals could be transmitted. In April 1872 William Henry Ward received U. A few months after Ward received his patent, Mahlon Loomis of West Virginia received U. The patented system claimed to utilize atmospheric electricity to eliminate the overhead wire used by the existing telegraph systems. It did not contain diagrams or specific methods and it did not refer to or incorporate any known scientific theory. It was similar to William Henry Ward’s patent.
In the United States, Thomas Edison, in the mid-1880s, patented an electromagnetic induction system he called “grasshopper telegraphy”, which allowed telegraphic signals to jump the short distance between a running train and telegraph wires running parallel to the tracks. Forms of Wireless telephony is recorded in four patents for the photophone, invented jointly by Alexander Graham Bell and Charles Sumner Tainter in 1880. In the early 1890s Nikola Tesla began his research into high frequency electricity. Tesla’s primary interest in wireless phenomenon was as a power distribution system although he proposed by 1893 that it could also incorporate communication. Various scientists proposed that electricity and magnetism were linked.
Around 1800 Alessandro Volta developed the first means of producing an electric current. In 1831, Michael Faraday began a series of experiments in which he discovered electromagnetic induction. Between 1861 and 1865, based on the earlier experimental work of Faraday and other scientists and on his own modification to Ampere’s law, James Clerk Maxwell developed his theory of electromagnetism, which predicted the existence of electromagnetic waves. Oliver Heaviside, later reformulated Maxwell’s original equations into the set of four vector equations that are generally known today as Maxwell’s equations. Imagine feelings when the differential equations he had formulated proved to him that electromagnetic fields spread in the form of polarised waves, and at the speed of light! To few men in the world has such an experience been vouchsafed it took physicists some decades to grasp the full significance of Maxwell’s discovery, so bold was the leap that his genius forced upon the conceptions of his fellow-workers. From a long view of the history of the world—seen from, say, ten thousand years from now—there can be little doubt that the most significant event of the 19th century will be judged as Maxwell’s discovery of the laws of electromagnetism.
The American Civil War will pale into provincial insignificance in comparison with this important scientific event of the same decade. Berend Wilhelm Feddersen, a German physicist, in 1859, as a private scholar in Leipzig, succeeded in experiments with the Leyden jar to prove that electric sparks were composed of damped oscillations. In 1870 the German physicist Wilhelm von Bezold discovered and demonstrated the fact that the advancing and reflected oscillations produced in conductors by a capacitor discharge gave rise to interference phenomena. It had been proposed in 1879 to German physicist Heinrich Rudolf Hertz that he try to prove Maxwell’s theory of electromagnetism but he could not see any way to build an apparatus to experimentally test the theory. The first of the papers published, “On Very Rapid Electric Oscillations”, gives an account of the chronological course of his investigation, as far as it was carried out up to the end of the year 1886 and the beginning of 1887.
1887 experimental setup of Hertz’s apparatus. Hertz was able to have some control over the frequencies of his radiated waves by altering the inductance and capacitance of his transmitting and receiving antennas. Hertz did not devise a system for practical utilization of electromagnetic waves, nor did he describe any potential applications of the technology. Hertz was asked by his students at the University of Bonn what use there might be for these waves. This is just an experiment that proves Maestro Maxwell was right, we just have these mysterious electromagnetic waves that we cannot see with the naked eye. Hertz died in 1894, and the art of radio wave communication was left to others to implement into a practical form.
Towards the end of 1875, while experimenting with the telegraph, Thomas Edison noted a phenomenon that he termed “etheric force”, announcing it to the press on November 28. On that day in August 1894, Lodge demonstrated the reception of Morse code signalling via radio waves using a “coherer”. He later improved Branly’s coherer by adding a “trembler” which dislodged clumped filings, thus restoring the device’s sensitivity. Electric Telegraphy”, that made wireless signals using a Ruhmkorff coil for the transmitter and a Branly coherer for the detector.
This patent utilized the concept of “syntonic” tuning. In 1912 Lodge sold the patent to Marconi. In 1894 Lodge showed that the Branly coherer could be employed to transmit telegraphic signals, and in order that the filings should not remain “cohered” after the cessation of the electric oscillations, he devised an electro-mechanical “tapper” on the principle of the ordinary “buzzer,” or electric door-bell, the hammer of which was caused to tap the glass tube as long as the electric oscillations continued. In November 1894, the Indian physicist, Jagadish Chandra Bose, demonstrated publicly the use of radio waves in Calcutta, but he was not interested in patenting his work. The receiver at this distance still had energy enough to make a contact which set a bell ringing, discharged a pistol, and exploded a miniature mine. The form of ‘Coherer’ devised by Professor Bose, and described by him at the end of his paper ‘On a new Electro Polariscope’ allowed for the sensibility and range to appear to leave little to be desired at the time.