File:Southworth demonstrating waveguide.jpg
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editDescriptionSouthworth demonstrating waveguide.jpg |
English: Demonstration in 1938 of the waveguide before the Institute of Radio Engineers by the inventor, Bell Telephone Laboratory scientist George C. Southworth (left). Behind the blackboard (right) were several vacuum tube oscillators producing 1.5 GHz (8 inch, 20 cm) microwaves of different modes. He demonstrated that they could pass through the 25 ft flexible metal waveguide and be detected by a receiver consisting of a silicon diode coupled to an amplifier and galvanometer. He demonstrated further properties of the waves:
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Date | |
Source | Retrieved March 28, 2015 from "Four inch waves turn science topsy-turvy" in Short Wave and Television magazine, Popular Book Corp., New York, Vol. 8, No. 12, April 1938, p. 669 on http://www.americanradiohistory.com |
Author | Unknown authorUnknown author |
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This 1938 issue of Short Wave and Television magazine would have the copyright renewed in 1966. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. Search of the Renewals for Periodicals for 1965, 1966, and 1967 show no renewal entries for Short Wave and Television. Therefore the copyright was not renewed and it is in the public domain. |
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This work is in the public domain because it was published in the United States between 1929 and 1963, and although there may or may not have been a copyright notice, the copyright was not renewed. For further explanation, see Commons:Hirtle chart and the copyright renewal logs.
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