File:Reflective array VHF television antenna 1954.jpg
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Reflective_array_VHF_television_antenna_1954.jpg (355 × 392 pixels, file size: 72 KB, MIME type: image/jpeg)
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[edit]DescriptionReflective array VHF television antenna 1954.jpg |
English: A widely-used type of reflective array television antenna, the Channel-Master model 325-2 from 1954, used to receive US VHF analog television channels 2 to 13, 54 to 213 MHz. It consists of multiple folded dipole driven elements (on left) connected by a 300Ω twin lead feedline to the television set, mounted in front of a flat grid reflector of horizontal rods. The reflector serves to reflect the radio waves back toward the dipoles, increasing the gain. Two different lengths of folded dipole and reflector rods are used to cover the entire VHF band. The VHF television band is divided into two subbands: VHF low (Band I), channels 2-6, 54-88 MHz, and VHF high (Band III), channels 7-13, 174-213 MHz. These bands are too widely separated in frequency to be covered by a single set of antenna elements. The two large folded dipoles, along with the longer reflector rods, cover the low band, while the 4 smaller dipoles, and the shorter reflector rods cover the high band. The elements are devided into two stacked "bays" which increases gain. A TV antenna like this that covered all the VHF channels was called an "all-VHF" antenna. Graphs by Channel-Master on p. 82 show the antenna has a gain of ~5 dBd over channels 2-6, 8-9 dBd over channels 7-13, and up to 9 dBd on portions of the UHF band. The advantage of the reflective array was that it achieved the high gain needed for fringe reception without the narrow bandwidth of the common Yagi antennas. Caption: "An all-VHF band TV antenna, two-bay array, with reflector screen." |
Date | |
Source | Retrieved August 5, 2014 from Edward M. Noll and Matthew Mandl, "The Continuing Evolution in Television Antennas" in Radio and Television News magazine, Ziff-Davis Publishing Co., New York, Vol. 51, No. 5, May 1954, p. 65, fig. 3 on American Radio History site |
Author | Edward M. Noll and Matthew Mandl |
Permission (Reusing this file) |
This 1954 issue of Radio and Television News magazine would have the copyright renewed in 1982. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. [1] Search of the Renewals for Periodicals for 1978 and later show no renewal entries for Radio and Television News. Therefore the magazine's copyright was not renewed and it is in the public domain. |
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[edit]Public domainPublic domainfalsefalse |
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 ∙ +/− |
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current | 17:23, 3 May 2021 | 355 × 392 (72 KB) | Materialscientist (talk | contribs) | Tidied | |
17:41, 23 September 2014 | 355 × 392 (29 KB) | Chetvorno (talk | contribs) | User created page with UploadWizard |
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