| Author |
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Alsworld
| | Posted on Saturday, September 06, 2003 - 9:04 pm: | 
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Hey all,
I just came back from a camping trip here in the Pacific North West. Saw what has got to be one of the largest (or larger category) antennas in the world. Here goes:
Picture a bunch of center fed dipoles (approximately 8 to 10), run parallel to each other. The center conductors all come down and join together via towers. Now these are much more complex than a simple dipole, but being it looks about the same relative to how they are constructed, that is what I will refer to it as for simplicity. Read below.
Now, here are the details. They run from one mountain top to another mountain top. The towers on either side are 200 ft high. Those towers sit on top of mountains where height's are approx 3,200ft on both sides (mountains only, towers extend 200 ft above these).
The longest horizontal span of one of (the dipoles) is approx 9,000 ft.
The drop from center of antenna to towers below is approx 1200 ft.
The area (underneath the antenna) covers 640 acres.
Frequency range is VLF.
Worldwide, 24/7/365.
This thing was impressive! Cool beans for sure.
Alsworld |
mikefromms
| | Posted on Sunday, September 07, 2003 - 6:41 am: |
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And I thought I had a big antenna. I bet that thing can walk the dog!
mikefromms |
Bruce
| | Posted on Sunday, September 07, 2003 - 9:20 am: |
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Now to get the wife to let you take it home |
Taz
| | Posted on Sunday, September 07, 2003 - 8:04 pm: |
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are you sure it was an antenna and not a mountain lift? |
Alsworld
| | Posted on Sunday, September 07, 2003 - 8:32 pm: |
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Taz, it was an antenna for sure. Inside the area, there was a mockup and pictures of it's creation, some tubes that power the amplifiers, etc. It was there where I got all the information about length and stuff. Outside, you could see it as well. I don't know the power of this thing but just one of the tubes drew over 600 amps. I don't know how many it contained or what the voltage feeding them was.
It's used to talk to submerged submarines, and obviously military.
I found a few links but they don't say much, one very weak arial photo and some other general news. It was really interesting.
Alsworld |
Bigbob
| | Posted on Sunday, September 07, 2003 - 9:04 pm: |
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Got a pic,hmmmmm?lol. |
boxman
| | Posted on Sunday, September 07, 2003 - 10:22 pm: |
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Alsworld, you must have been up near Jim Creek. Uncle Sam is pretty hush, hush about the "real details" on this setup.
boxman |
Taz
| | Posted on Sunday, September 07, 2003 - 10:26 pm: |
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Subs talk on 1750 meters. There was a big post about it, with me trying to find the wave length of an antenna on 1750 meters thats 1/4 mile long, and I think it was still only a 103:1 wave antenna. |
Taz
| | Posted on Sunday, September 07, 2003 - 10:28 pm: |
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NLK – Jim Creek Washington
NLK was built in 1952 to service the submarines of the pacific fleet, and at that time it was the most powerful transmitter in the world. The design took advantage of the geography of the area to moor the ends of the capacitate "Top Hat" on a structure that was different than a conventional metal tower. In this case the tops of two ranges of mountains (Blue at 920m/3000ft and Wheeler at 920m/3200ft) were used as those anchor points for a series of 61m/200ft stub towers. The results were long spans of 1 inch thick (37 strands of No. 7 wire) copper antenna wire. The length of the spans range between 8700 ft to 5640 ft per leg as they zigzag down the valley (see figure 4). The downleads, which represent the vertical portion of the antenna, are made out of hollow copper tubing that is .91 inches in diameter, with lengths ranging from 366m/1200ft to 306m/1000ft due to variations in the height of the valley floor. The RF signal itself is fed to the downleads using a bus system, which is located at 27m/125 ft above the valley floor. While the structure is quite large, it is also sensitive in its tuning. To give an example of this, it has been found that the resonant frequency of the structure changed during the summer due to the increase in height of vegetation in the valley. As a result, regular cutting back of the foliage in the valley was needed to keep the antenna in tune. |
Taz
| | Posted on Sunday, September 07, 2003 - 10:31 pm: |
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Read this, 192KW!
http://www.fas.org/nuke/guide/usa/c3i/vlf.htm
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Bigbob
| | Posted on Monday, September 08, 2003 - 5:03 am: |
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There is an ELF underground antenna array in the U.P. of mich.on federal property for talking to subs in all the oceans. |
Alsworld
| | Posted on Monday, September 08, 2003 - 9:08 pm: |
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Boxman nailed it and a good follow-up from Taz. Yep, that is where I was at and the antenna I was describing.
Bigbob, not exactly what you were looking for but here is some rough stuff. I typed in "Jim Creek Naval" into a Yahoo search engine and previously I found the picture of the mock-up scale. Click on it to enlarge and it kind of shows what it looks like. This link is not the site, but may give you an idea of the size.
http://cryptome2.org/jcrs-eyeball.htm
You guys are good!
Alsworld
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Straycat
| | Posted on Monday, September 08, 2003 - 9:38 pm: |
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Used not only for submerged subs but also for the Minutman and Peackeeper missile launch control centers buried in Wyoming, North Dakota, Montana. Survivable Low Frequency Communication System SLFCS |
Mr_Rf
| | Posted on Thursday, September 11, 2003 - 3:02 am: |
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Sounds like a pretty big lightning arrestor to me!
I think the buried transducers make better since for sub-comms. |
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