This is a file from the Wikimedia Commons

File:Split-anode magnetron.jpg

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Split-anode_magnetron.jpg(345 × 258 pixels, file size: 15 KB, MIME type: image/jpeg)


English: Split-anode magnetron tube, an obsolete microwave vacuum tube invented by Albert Hull at General Electric in 1920. One of the first oscillators that could produce frequencies in the gigahertz range, it was used until the modern cavity magnetron was invented in 1940. This tube, used in 1935 in early German experiments in radar was manufactured by AEG/Telefunken and could generate 10 centimeter (3 GHz) microwaves. The image on the left shows the bare tube, about 11 cm tall; on the right shows the tube mounted for use between the poles of a strong permanent magnet.

Alterations to image: combined two separate images

Source Retrieved October 24, 2014 from "Microwaves to detect aircraft" in Electronics magazine, McGraw-Hill Publishing Co., New York, Vol. 8, No. 9, September 1935, p. 18 on
Author Unknown
Unknown author
(Reusing this file)

This 1935 issue of Electronics magazine would have the copyright renewed in 1963. 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 1962, 1963, and 1964 show no renewal entries for Electronics. Therefore the copyright was not renewed and it is in the public domain.


Public domain
This work is in the public domain because it was published in the United States between 1923 and 1963 and although there may or may not have been a copyright notice, the copyright was not renewed. Unless its author has been dead for the required period, it is copyrighted in the countries or areas that do not apply the rule of the shorter term for US works, such as Canada (50 pma), Mainland China (50 pma, not Hong Kong or Macao), Germany (70 pma), Mexico (100 pma), Switzerland (70 pma), and other countries with individual treaties. See Commons:Hirtle chart for further explanation.

Deutsch | English | español | français | italiano | 日本語 | 한국어 | македонски | português | português do Brasil | русский | українська | 中文(台灣)‎ | +/−

Flag of the United States

File history

Click on a date/time to view the file as it appeared at that time.

current07:49, 26 May 2015Thumbnail for version as of 07:49, 26 May 2015345 × 258 (15 KB)ChetvornoUser created page with UploadWizard
The following pages on the English Wikipedia link to this file (pages on other projects are not listed):