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Author Topic: Delta Loop -OK- Forgot my Geometry  (Read 7172 times)
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Bill, KD0HG
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304-TH - Workin' it
« on: August 04, 2012, 08:49:13 PM »
OK...Assume a delta loop, top apex high on a tower at ~80 feet.

Each leg of triangular loop is 88' long.
Each apex is 120 degrees.

How far off the ground would the bottom horizontal leg be??

Bill
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Ralph W3GL
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« Reply #1 on: August 04, 2012, 09:39:57 PM »
Bill,

Won't go into the math (hint, it's a TRIG function)...  

Just pull out some graft paper, you know the stuff with all the little squares on it, give each square a value, draw your design and you should be able to see the base to surface distance at a glance with a scale/ruler...  I've done this on many antenna/tower setups...     GL...
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73,  Ralph  W3GL 

"Just because the microphone in front of you amplifies your voice around the world is no reason to think we have any more wisdom than we had when our voices could reach from one end of the bar to the other"     Ed Morrow
KF1Z
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Are FETs supposed to glow like that?
« Reply #2 on: August 04, 2012, 10:18:21 PM »
3.8  feet off the ground

h = √3 / 2 * a
h= height
a= equilateral leg length

( 0.866 ) * 88 = 76.2

80 - 76.2 = 3.8



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http://www.genesisradio.com.au/
Bill, KD0HG
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304-TH - Workin' it
« Reply #3 on: August 05, 2012, 10:18:01 AM »
Thank you, gents.

Didn't have any gridded paper handy- LOL

Bill
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Steve - K4HX
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« Reply #4 on: August 05, 2012, 09:30:05 PM »
Nice calculator here.

http://mysite.verizon.net/ka1fsb/loopcalc.html
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WA1GFZ
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« Reply #5 on: August 05, 2012, 10:22:58 PM »
good chance it won't work worth a crap. Better off an inverted Vee with the ends pulled out as far as possible.
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aa5wg
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« Reply #6 on: August 06, 2012, 09:46:27 AM »
Bill:

KF1Z nailed it.  His calculations match mine.  3.8 feet or exactly 3.790 feet or 3 feet 9.48 inches above the ground  (3 feet 9 and 1/2 inches).

Chuck
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W3RSW
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Rick & "Roosevelt"
« Reply #7 on: August 06, 2012, 10:06:35 AM »
You all nailed it if the apex angle is 60 degrees.   Grin
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RICK  *W3RSW*
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Are FETs supposed to glow like that?
« Reply #8 on: August 06, 2012, 10:43:02 AM »
Quote from: W3RSW on August 06, 2012, 10:06:35 AM
You all nailed it if the apex angle is 60 degrees.   Grin


He said "Each leg of triangular loop is 88' long."

If all the legs are the same length, then all three angles have to be the same.  Grin

Yes, different calculation for isosceles or scalene triangles.
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WA1GFZ
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« Reply #9 on: August 08, 2012, 04:28:58 PM »
I've never had any luck using a loop with the base close to the ground. Wasted too many hours trying.
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W3RSW
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Rick & "Roosevelt"
« Reply #10 on: August 09, 2012, 04:59:48 PM »
can you turn it upside down and be somewhat more effective?
-or is the whole thing too close to the ground?
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RICK  *W3RSW*
N4zed
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« Reply #11 on: August 09, 2012, 08:24:28 PM »
Or you can bring two of the points up to match the upper most one....

http://home.comcast.net/~n4zed/site/?/page/N4zed_Loop_2/&PHPSESSID=59c1012508dfe4016757f514c2c43f53


Ken
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Ken<br />N4zed
Steve - K4HX
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« Reply #12 on: August 12, 2012, 09:16:03 PM »
The average height is greater with the inverted delta loop and there is less coupling to the ground. This is the config I use on my 40 meter loops.

S



Quote from: W3RSW on August 09, 2012, 04:59:48 PM
can you turn it upside down and be somewhat more effective?
-or is the whole thing too close to the ground?

* loopsatsunset.jpg (295.35 KB, 768x1024 - viewed 534 times.)
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