File:Old UHF-VHF television antenna.jpg
![File:Old UHF-VHF television antenna.jpg](https://upload.wikimedia.org/wikipedia/commons/thumb/2/23/Old_UHF-VHF_television_antenna.jpg/800px-Old_UHF-VHF_television_antenna.jpg?20160411145147)
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Summary
[edit]DescriptionOld UHF-VHF television antenna.jpg |
English: A common sight in North America today are forgotten television antennas like this one, found in a Toronto suburb. A number of the "elements" are bent or broken, and the antenna like has poor performance, but it remains in place because removing it would cost money.
North American antennas of the 1960s through 1990s almost always looked like this example. They actually consist of two antennas, one in front of the other. The "arrow" shape at the front (left side) is a UHF antenna in the form of a Yagi-Uda array with a corner reflector. Behind it (right) is a log-periodic (L-P) design for VHF signals. Running between the elements in the L-P side one can see a thin metal wire that connects those elements to the figure-eight loop of the Yagi. A 300-ohm twin-lead wire can be seen connected to the loop. This design was very common in the era when television signals were broadcast on both VHF and UHF, which lasted from the 1950s until 2009 when most VHF stations were turned over to other uses. Antennas of this type were very large and highly directional, which required them to be mounted on sturdy masts and use a rotator to point them to the desired signal - the rotator is the cone-shaped box below the antenna, its control wires can be seen. The combination of Yagi and L-P worked well because the antennas could be mounted in-line along a common boom. The Yagi, especially the reflector, had some effect on the operation of the L-P behind it, but not enough to demand the use of two separate antennas, at least in most cases. For modern use, only the Yagi area at the front of the antenna would be needed. However, the switch to mostly UHF meant that the UHF portion no longer had to be linear so that it would lie in-line with the L-P, and modern UHF antennas generally use some form of bowtie array which is much lighter and smaller than the equivalent Yagi. |
Date | |
Source | Own work |
Author | Maury Markowitz |
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 14:51, 11 April 2016 | ![]() | 3,872 × 2,592 (1,021 KB) | Maury Markowitz (talk | contribs) | User created page with UploadWizard |
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Date and time of data generation | 08:13, 8 November 2015 |
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Orientation | Normal |
Horizontal resolution | 72 dpi |
Vertical resolution | 72 dpi |
Software used | Photos 1.5 |
File change date and time | 08:13, 8 November 2015 |
Date and time of digitizing | 08:13, 8 November 2015 |
Color space | sRGB |