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3 Half-Wave Dipole




 
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Author Topic: 3 Half-Wave Dipole  (Read 1580 times)
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Ed WA4NJY
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« on: July 18, 2022, 05:02:40 PM »


   I would like to have a dedicated bi-directional antenna for 15 meters.  A little gain would help.

   Is the 3/2 wave dipole have any real advantage over a regular half-wave at same height?

   Either one is an easy install.   Any input will be muchly appreciated.

   Thanks,

        Ed WA4NJY
        Bradenton, Fl
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M0VRF
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« Reply #1 on: July 19, 2022, 12:03:15 PM »

Works on 40 as well with conventional pattern however 3/2 has deep nulls, close to gnd or inv V prob omni anyway..
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WU2D
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CW is just a narrower version of AM


« Reply #2 on: August 14, 2022, 09:19:27 AM »

Just another proven solution: A vertical loop only requires two supports and two lower guys- it is basically two dipoles in phase and is bidirectional. When square it is easily matched with a 2:1 Balun. When Rectangular you can easily hit 50 Ohms. Here is a nice article showing a 15M and nested 10M loop setup.

https://va3stl.wordpress.com/2010/08/11/dual-band-rectangular-loop-antenna-for-15m-and-10m/
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These are the good old days of AM
K9MB
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« Reply #3 on: August 14, 2022, 10:06:12 AM »

Maybe you would like an extended double zepp.
It gives you two half waves in phase and some gain over a dipole plus a clean bi-directional pattern.
I built an array using this antenna for 20 meters that included passive reflectors and directors so that it became two 3 element yagis mounted side by side.
It can also be built as an inverted vee.

https://www.google.com/search?q=extended+double+zepp+inverted+v&rlz=1C9BKJA_enUS931US931&oq=extended+double+zepp&aqs=chrome.2.69i57j0i512l2j0i22i30l3.16612j1j7&hl=en-US&sourceid=chrome-mobile&ie=UTF-8


I agree that the delta or quad 1 wavelength loop is an excellent antenna.
73, Mike
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WA4WAX
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« Reply #4 on: August 14, 2022, 06:34:49 PM »

An 8JK would be made to order for your situation. 
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Ed WA4NJY
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« Reply #5 on: August 15, 2022, 06:17:01 PM »


   Many thanks to all who replied to my question.  I am leaning toward a rectangle loop for 15.  The project will have to wait until weather cools later this year.

               73,
                    Ed  WA4NJY
                    Bradenton, Fl
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R. Fry SWL
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Broadcast Systems Engineer (retired)


WWW
« Reply #6 on: August 16, 2022, 07:01:27 AM »


   I would like to have a dedicated bi-directional antenna for 15 meters.  A little gain would help.

   Is the 3/2 wave dipole have any real advantage over a regular half-wave at same height?

The study below may be one solution.  This configuration smooths out the deep nulls in the pattern of a linear 1.5WL antenna, and has a fair amount of gain over a linear, 0.5WL horizontal dipole.

RF (W9XMT)

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WA4WAX
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« Reply #7 on: August 16, 2022, 12:05:26 PM »

Try this simulation:

15 meter 8JK 25 feet up and 18 feet up.

Dimensions:

Wires 18 feet long.  5.5 feet separation.  End fed with 3/4 wave Zepp feeder.

My money says it beats the loop.
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K2WW
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« Reply #8 on: August 17, 2022, 07:17:52 AM »

Lookup
"half-square" bi-directional and low to ground/low angle radiation

73
Dean
K2WW
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K9MB
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« Reply #9 on: August 17, 2022, 09:42:05 AM »

Lookup
"half-square" bi-directional and low to ground/low angle radiation

73
Dean
K2WW

Very interesting antenna. I had not considered one because My towers were only 60 feet, but Rudy Severns N6LF published this article in ARRL Antenna Compendium 5 and he also has it on his site. Great idea. MB

https://rudys.typepad.com/ant/files/antenna_halfsquare_array.pdf
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