File:First turnstile antenna W8XH Buffalo NY 1936.jpg

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Summary

Description	English: Probably the first turnstile antenna array, constructed in 1936 on the roof of the Statler Hotel, Buffalo, New York, for experimental "ultra short wave" AM station W8XH which broadcast on 41 MHz for a few years. The turnstile antenna was invented by engineer George Brown at RCA in 1935. This example consisted of 6 stacked turnstile "bays" on a 70 foot mast. Each "bay" consists of two crossed 3.6 meter dipole driven elements, fed in quadrature (with a 90° phase difference). It radiated horizontally polarized radio waves with an omnidirectional pattern. The purpose of the multiple bays is to increase the gain in horizontal directions and reduce the power radiated into the sky or down toward the earth. The source says it gave good reception for a radius of 25 to 30 miles. The turnstile antenna was used as a VHF transmitting antenna in some of the first FM stations during the 40s, but its horizontal polarization had the disadvantage that the signal strength in a receiver varied depending on the orientation of the antenna. FM stations now broadcast in circular polarization. Caption: Photos above and to the right show the new "turnstile" antenna array in use at short-wave station W8XH in Buffalo, N. Y. A 70 foot pole supports the antenna array.
Date	July 1936
Source	Retrieved March 24, 2015 from "Turnstile antenna array at W8XH" in Short Wave Craft magazine, Popular Book Corp., New York, Vol. 7, No. 3, July 1936, p. 138 on http://www.americanradiohistory.com
Author	Unknown authorUnknown author
Permission (Reusing this file)	This 1936 issue of Short Wave Craft magazine would have the copyright renewed in 1964. 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 1963, 1964, and 1965 show no renewal entries for Electronics. Therefore the copyright was not renewed and it is in the public domain.

Licensing

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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