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1 Discovery and exploitation. 2 ... like other electromagnetic radiation such as light, radio waves can alternatively ... in the medium wave and longwave bands, due ...
May 1895: After reading about Lodge's demonstrations, the Russian physicist Alexander Popov builds a "Hertzian wave" (radio wave) based lightning detector using a coherer. November 1895: Jagdish Chandra Bose sets up a demonstration of radio microwave at the Town Hall in Calcutta where he ignites gunpowder in a nearby room and rings a bell. [30]
Early experiment demonstrating refraction of microwaves by a paraffin lens by John Ambrose Fleming in 1897. After their discovery many scientists and inventors experimented with transmitting and detecting "Hertzian waves" (it would take almost 20 years for the term "radio" to be universally adopted for this type of electromagnetic radiation). [8]
The radio waves carry the information across space to a receiver, where they are received by an antenna and the information extracted by demodulation in the receiver. Radio waves are also used for navigation in systems like Global Positioning System (GPS) and navigational beacons, and locating distant objects in radiolocation and radar.
Before the discovery of electromagnetic waves and the development of radio communication, there were many wireless telegraph systems proposed and tested. [4] In April 1872 William Henry Ward received U.S. patent 126,356 for a wireless telegraphy system where he theorized that convection currents in the atmosphere could carry signals like a telegraph wire. [5]
The effects of electromagnetic radiation upon living cells, including those in humans, depends upon the radiation's power and frequency. For low-frequency radiation (radio waves to near ultraviolet) the best-understood effects are those due to radiation power alone, acting through heating when radiation is absorbed.
A new type of stellar object has been discovered releasing energetic bursts of radio waves every 22 minutes. ... The unfamiliar object released giant bursts of energy and beamed out radiation ...
Karl Guthe Jansky (October 22, 1905 – February 14, 1950) was an American physicist and radio engineer who in April 1933 first announced his discovery of radio waves emanating from the Milky Way in the constellation Sagittarius.