File:Broadcast antenna counterpoise.jpg

From Wikimedia Commons, the free media repository
Jump to navigation Jump to search

Broadcast_antenna_counterpoise.jpg (683 × 342 pixels, file size: 30 KB, MIME type: image/jpeg)

Captions

Captions

Add a one-line explanation of what this file represents

Summary

[edit]
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

[edit]
Public domain
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.

العربية ∙ Deutsch ∙ English ∙ español ∙ français ∙ galego ∙ italiano ∙ 日本語 ∙ 한국어 ∙ македонски ∙ português ∙ português do Brasil ∙ русский ∙ sicilianu ∙ slovenščina ∙ українська ∙ 简体中文 ∙ 繁體中文 ∙ +/−

Flag of the United States
Flag of the United States

File history

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

Date/TimeThumbnailDimensionsUserComment
current00:49, 21 March 2014Thumbnail for version as of 00:49, 21 March 2014683 × 342 (30 KB)Chetvorno (talk | contribs)User created page with UploadWizard

You cannot overwrite this file.

The following page uses this file:

File usage on other wikis

The following other wikis use this file:

Metadata

This file contains additional information such as Exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. The timestamp is only as accurate as the clock in the camera, and it may be completely wrong.

Retrieved from "https://commons.wikimedia.org/w/index.php?title=File:Broadcast_antenna_counterpoise.jpg&oldid=834617247"