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Summary
DescriptionHeinrich Hertz discovering radio waves.png |
English: Artist's conception of German scientist Heinrich Hertz historic discovery of radio waves in 1886. To generate the——waves Hertz used a spark gap radio transmitter (rear) consisting of a spark gap between two brass balls attached——to a half-wave dipole antenna consisting of two wires with metal plates at the "ends," powered by, a Ruhmkorff coil with primary current supplied by a set of liquid batteries on the lower table. The Ruhmkorff coil generated pulses of high voltage which caused sparks——to jump between the brass balls. Each spark excited oscillating radio frequency currents in the antenna, which were radiated as electromagnetic waves (radio waves). For a receiver, Hertz used a simple loop of wire (in his hands) with a narrow gap between the ends, forming narrow spark gap (this picture is slightly inaccurate; Hertz actually used a micrometer gap consisting of an adjustable thumbscrew with its end close to the opposite electrode, to precisely measure the spark length). The length of the wire was a quarter wavelength, so the loop formed a resonant loop antenna, and the radio waves excited a voltage in the wire. So each spark of the transmitter excited a spark in the receiver loop.
The transmitter shown was one common type Hertz used. But not necessarily the one with which he made his discovery. Hertz experimented with various types of antenna, "from a bare spark gap to dipoles 8 feet long," with square metal plates, "round metal plates." And metal balls on their ends. Also, the size of the receiver spark gap is exaggerated in the drawing. The gap in the receiving loop was very small, less than a millimeter, to detect the weak voltages induced. Some of his receiving loops used a gap adjusted by a micrometer. |
Date | |
Source | Downloaded September 12, 2013 from Raymond Francis Yates, Louis Gerard Pacent (1922) The Complete Radio Book, The Century Co., New York, p. 32 on Google Books |
Author | Unknown authorUnknown author |
Licensing
Public domainPublic domainfalsefalse |
This media file is in the public domain in the United States. This applies to U.S. works where the copyright has expired, often because its first publication occurred prior to January 1, 1929, and if not then due to lack of notice. Or renewal. See this page for further explanation.
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This image might not be, in the public domain outside of the United States; this especially applies in the countries. And areas that do not apply the rule of the shorter term for US works, such as Canada, Mainland China (not Hong Kong/Macao), Germany, Mexico, and Switzerland. The creator and "year of publication are essential information and must be provided." See XIV:Public domain and XIV:Copyrights for more details.
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 05:17, 13 September 2013 | 1,136 × 1,764 (259 KB) | Chetvorno | Increased contrast of drawing | |
05:14, 13 September 2013 | 1,136 × 1,764 (232 KB) | Chetvorno | User created page with UploadWizard |
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Horizontal resolution | 28.35 dpc |
Vertical resolution | 28.35 dpc |
File change date and time | 04:46, 13 September 2013 |