File:Broadcast antenna counterpoise.jpg
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Summary
| Description |
English: Base of antenna mast of AM radio station KTBS (now KEEL) in Shreveport, Louisiana, USA, showing a counterpoise ground screen. The ground screen is a network of horizontal radial copper wires extending out from the base of the mast, suspended on posts above the white helix house, attached to the antenna's ground system. Its purpose is to prevent excessive ground currents, reducing transmitter power dissipated in ground resistance. A counterpoise is similar to a ground screen but extends out further, up to a quarter-wavelength, replacing the ground wires entirely. Alterations to image: lightened dark areas to bring out ground screen more clearly against sky. |
| Date | |
| Source | Retrieved from Edmund A. Laport, Radio Antenna Engineering, McGraw-Hill Publishing Co., New York, 1952, p. 54, fig 1.14 on David Platt's webpage for this book |
| Author | Edmund A. Laport |
| Permission (Reusing this file) |
The copyright for this book Radio Antenna Engineering should have been renewed in 1980. A search of the US Copyright Office online database covering 1978 to the present shows no copyright renewal for that author name or title. Therefore the copyright was not renewed and the book is in the public domain. |
Licensing
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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. Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 00:49, 21 March 2014 | | 683 × 342 (30 KB) | Chetvorno | User created page with UploadWizard |
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