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Author Topic: What Kind of Antenna is This?  (Read 3224 times)
KL3HY
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Posts: 117




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« on: March 29, 2013, 12:30:13 PM »

I'm thinking this is a very large log periodic, using wire for the elements, but I'm not sure:

http://www.tibor.org/antenna.html

Neither my wallet nor my yard can support an antenna like this, but I was just curious. 

Thanks,
Mike
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WB6BYU
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« Reply #1 on: March 29, 2013, 04:52:53 PM »

Yes, from what I can see of the wire elements in the overhead photo it is
a log-periodic array.
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KL3HY
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Posts: 117




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« Reply #2 on: March 29, 2013, 11:09:23 PM »

I think that's got to be the biggest rotatable log periodic I've ever seen any pictures of--the shortest element width is almost 20 ft. and the longest is about 100 ft, very roughly speaking, based on Google maps' scale measure.

Note that the overhead photo shows the array pointing to the relative lower left.  Also the two boom ends that have angled supports, and the third (lower left) has a straight support. 


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K7KBN
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« Reply #3 on: March 30, 2013, 10:46:50 AM »

What is "www.tibor.org"??  "Hide your coffee"...??
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73
Pat K7KBN
CWO4 USNR Ret.
NH7O
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« Reply #4 on: March 30, 2013, 10:59:07 AM »

I have seen antennas like these in the South Bay area, and also on the East Coast. I believe they are government installations. Probably ~5-20 MHz. FAA comes to mind for some reason.
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KL3HY
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« Reply #5 on: March 30, 2013, 01:13:26 PM »

What is "www.tibor.org"??  "Hide your coffee"...??

Sorry--inside family joke.  Most of the people in my family drink coffee by the gallon and when I set up the tibor.org domain I just created a little placeholder page and thought that would be appropriate.
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KL3HY
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Posts: 117




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« Reply #6 on: March 30, 2013, 01:23:15 PM »

I have seen antennas like these in the South Bay area, and also on the East Coast. I believe they are government installations. Probably ~5-20 MHz. FAA comes to mind for some reason.


The antenna in the two images is one I've seen at many Air Force and other Gov't sites.  We have a couple at Elmendorf here in AK, and the one in the images I posted is at the Davidsonville, MD transmitter site for the HFGCS.  I think it's manufactured by Rockwell/Collins, but I may be wrong on that.

In the overhead image I included the scale so you can get a sense of the size of the thing--it's about 20 feet from tip to tip on the shortest elements, and about 100 feet for the longest.

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K7KBN
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« Reply #7 on: March 30, 2013, 04:46:01 PM »

What is "www.tibor.org"??  "Hide your coffee"...??

Sorry--inside family joke.  Most of the people in my family drink coffee by the gallon and when I set up the tibor.org domain I just created a little placeholder page and thought that would be appropriate.


Ah!  So the Google hits regarding Hungarian Freedom Fighters and so forth aren't too relevant for these antennas -- gotcha!  I thought I'd seen something like those quite a few years ago when I was on the way out to Adak via Reeve Airlines (Hail Mary Airlines).
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73
Pat K7KBN
CWO4 USNR Ret.
KL3HY
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Posts: 117




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« Reply #8 on: March 30, 2013, 06:29:31 PM »

Yep, no Hungarian freedom fighters here.   Grin

So if you commuted to/from Adak via Reeve, then you probably have the honor of being among the last people on Earth to fly on a revenue flight in a Lockheed Electra!

I think Adak also had a Wullenweber antenna.  The last one of those is still operational at Elmendorf, but I haven't actually seen it in person.
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KL3HY
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Posts: 117




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« Reply #9 on: March 31, 2013, 12:31:47 AM »

I think Adak also had a Wullenweber antenna. 

Here we go--the Adak Wullenweber's remains are still visible in Google Maps here:

   51.94266, -176.60047

Nothing very interesting, just a big cleared circular field where the antenna array used to be.

Mike
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K2DC
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« Reply #10 on: March 31, 2013, 07:58:51 AM »

Here's a bigger one for you, and it's still there:

45.160495, -69.850388

It's the Over-the-Horizon Radar transmit site near Moscow ME.  It's an FM-CW radar built by GE Aerospace in the mid-80's and I believe it's still at least semi-active.  Three sectors that cover 120 degrees each.  Each sector has 12-element dipole arrays on each of 5 sub-bands from 5-28 MHz.  Each element of each array is fed by a 100 KW transmitter (custom built by Continental) using 6" air dielectric coax feed lines. The elements are 45 degree polarization on the lowest two bands, and vertical on the other three.  All fed against a high backscreen and 750' of groundscreen.  I made several trips there in the late 80's.

One of the tricks to making a CW radar work is to maintain at least 120 dB of isolation between the transmit and receive antennas.  This system used 100 miles of the state of Maine for that - the receive site was near Columbia ME (never got there).  There was a West Coast system straddling the OR-CA border that finished acceptance testing around 1990 and was immediately mothballed.  Systems for the North Central US and Alaska were planned, but never even started - The Russians couldn't afford anything to throw over the Pole at us any more.  

BIG, BIG neat stuff.

73,

Don, K2DC
« Last Edit: March 31, 2013, 08:13:48 AM by K2DC » Logged
W8ATA
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Posts: 325




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« Reply #11 on: March 31, 2013, 07:00:00 PM »

No way!! You all got it wrong. This structure is what remains of a giant bird feeder located here in Newark, Ohio. The horizontal structural members supported a wooded platform and mounted in the center of it was a 50' high wooden silo. The wire which you think are elements of an antenna are actually perches for birds.  During the predawn hours of April 1st. of each year the silo was filled with bird seed from a train ore car on nearby siding.  With first light birds came by the millions from all over the world for this annual treat. Levels in the silo dropped rapidly but the ingenious development by local hams of the What Bird Meter monitored species and numbers of birds and alerted officials when to send for more seed. Don, K2DC, I am surprised you didn't remember this infamous structure from you were a little guy living here in Newark.   Wink

73 and keep smiling,
Russ
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K7KBN
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Posts: 2814




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« Reply #12 on: March 31, 2013, 10:33:00 PM »

Yep, no Hungarian freedom fighters here.   Grin

So if you commuted to/from Adak via Reeve, then you probably have the honor of being among the last people on Earth to fly on a revenue flight in a Lockheed Electra!


My one flight to/from Adak was in December 1974, where I was a member of a surveying team for one of the two YTBs (Large Yard Tugboats) that were assigned to Adak. 

Ever check out the VLF array at North West Cape, Australia?  I had a chance to get stationed there in the '60s, right when construction was about complete.  BUT - the Lord had other plans for me!
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73
Pat K7KBN
CWO4 USNR Ret.
KL3HY
Member

Posts: 117




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« Reply #13 on: February 27, 2014, 01:12:09 AM »

Just to close the loop on this one, I have it on good authority that the big log periodic antenna I mentioned at the start of this thread is manufactured by Antenna Products in Mineral Wells, TX.

http://www.antennaproducts.com/

Again, if only I had the money and yard space...

Mike
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WB3CQM
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Posts: 117




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« Reply #14 on: February 27, 2014, 04:16:44 AM »

If I had the money I would build this antenna

http://www.qrz.com/db/5N0OCH
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