File:Dipole radar altimeter antenna.jpg
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Summary
| Description |
English: A dipole antenna of a radar altimeter from an advertisement in a 1947 radio magazine. It was mounted on the bottom surface of an aircraft and transmitted radio waves which reflected from the ground. The altitude of the aircraft was calculated from the time it took the radio waves to return. This is a half-wave dipole; composed of two symmetrical elements each 1/4 wavelength long, insulated from each other with the white insulator. It is mounted 1/4 wavelength below the aircraft's body, so the aircraft's aluminum skin functioned as a reflecting surface to reinforce the outgoing wavefront. It is made of painted brass tubing, and was mounted parallel to the airstream to reduce air drag. The text gave no information about the operating frequency, but if the antenna is roughly 20 cm, long as it appears to be, the wavelength is around 40 cm so the operating frequency was in the UHF range, around 700 MHz. A coaxial cable feedline attached to the connector, bottom. |
| Date | |
| Source | Retrieved June 15, 2014 from Tele-Tech magazine, Caldwell-Clements Inc., Bristol, Connecticut, Vol. 6, No. 5, May 1947, p. 7 on American Radio History website |
| Author | Unknown author |
| Permission (Reusing this file) |
This image is from an advertisement without a copyright notice published in a 1947 magazine. In the United States, advertisements published in collective works (magazines and newspapers) are not covered by the copyright notice for the entire collective work. (See U.S. Copyright Office Circular 3, "Copyright Notice", page 3, "Contributions to Collective Works".) Since the advertisement was published before 1978 without a copyright notice, it falls into the public domain. |
Licensing
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This work is in the public domain in the United States because it was published in the United States between 1929 and 1977, inclusive, without a copyright notice. For further explanation, see Commons:Hirtle chart as well as a detailed definition of "publication" for public art. 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 (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.
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File history
Click on a date/time to view the file as it appeared at that time.
| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 18:49, 17 June 2014 | 771 × 474 (81 KB) | Chetvorno | User created page with UploadWizard |
File usage
The following pages on the English Wikipedia use this file (pages on other projects are not listed):
Global file usage
The following other wikis use this file:
- Usage on da.wikipedia.org
- Dipolantenne
- Usage on zh.wikipedia.org
- 雷達高度計
- 偶极子天线