File:Dipole radar altimeter antenna.jpg

Dipole_radar_altimeter_antenna.jpg (771 × 474像素,文件大小:81 KB,MIME类型:image/jpeg


摘要

描述
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.
日期
来源 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
作者 未知Unknown author
授权
(二次使用本文件)
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.

许可协议

本作品在美国属于公有领域,因为其于1929至1977年(包括)间在美国出版,且没有著作权声明。更多详情,请参见共享资源:赫特图表以及公共艺术品“出版”的详细说明。请注意此作品在对美国作品不适用较短期限法则的管辖区可能仍然受版权保护(基于作者的逝世日期),例如加拿大(作者逝世后50年)、中国大陆(作者逝世后50年,不包括香港和澳门)、德国(作者逝世后70年)、墨西哥(作者逝世后100年)、瑞士(作者逝世后70年)及其他有本地条约的国家。

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