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KNBR (AM 680) Antennas, Redwood City, CA, 2024 (cdn.masto.host)
submitted 1 year ago by to c/photography@fedia.io
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KNBR (AM 680) Antennas, Redwood City, CA, 2024.All the pixels, none of the sports, news, or weather, at flickr.com/photos/mattblaze/54#photography

Two radio antenna masts in a field. The taller mast, on the right, is a guyed tower with a hexagonal structure at the top. The shorter mast on the left, toward the background, is freestanding.
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[–] 1 point 1 year ago (1 child)

@mattblaze Radio and Photography technical expertise and explanations in one thread - what's not to love!A quick google indicates that the wavelength of 680kHz is approximately 440m.I was half expecting the antenna lengths to be an even fraction of a wavelength, but came up with 5/18ths for the lower section and 5/54 for the upper section before the effect of the hat.

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  • [–] [S] 1 point 1 year ago

    @BernardSheppard Yeah, MW wave antennas are almost never an exact standard size that might be used at higher frequencies (like 1/4 or 5/8 wave), especially because stations sometimes change frequencies. So everything is tuned.By the way, it's common for lower frequency antennas to be specified in degrees of a full wave. So this antenna is a total of 137º at 680 KHz (but electrically longer, because of the top hat).

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