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Author Topic: 160 meter 574' delta loop  (Read 4707 times)
VA3KBC
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« on: March 28, 2012, 07:10:29 PM »

Hi all.
A brief history. I tried getting my ham radio license back over 30 years ago.
Now just a few months away from my 60th birthday I thought I better give it another go.
Success and am now VA3KBC.
So with my newly aquired and greatly appreciated license I am looking at antennas.
I live on a farm and have two rows of tall ever green trees (pine trees) some reaching over 60 feet tall running parallel the drive way about 250' long.

I have purchased a G5RV 102' also Hy-Power 160 meter 268' dipole and a Hy-Power 40 66'.

The 268' is going to be a over the top at about 50' from 3 of the tallest pine trees.
The 40 meter 66' is also going to be a horizontal between a couple of pine trees also around that 40 to 50 ' height.
 
Now my next plan is to put up a 574' horizontal delta loop horizontal antenna going from my 40'x60' drive shed over my house (where I plan to go with ladder line down to the shack 15, 20' below) heading east to the pine tree at 55' high (190') then going south west (190')to the old maple tree at about 35 to 40' high then north 190' back to the drive shed about 25' high.


With everything I have read loops are pretty forgiving in their overall design. Round being the best, octagon, rectangle etc.
Anything I should be aware of? I have a 4:1 Balun coming from Array Solutions as well.
DXE-RR8B-HP remote switch and DXE-CC-8A control console.
A Kenwood TS590 in the shack and a  MFJ949E coming also.

Any suggestions will be welcome.
Don
VA3KBC  (my 2 Daughters names and my wifes . Kristina, Barb, Carol)
« Last Edit: March 28, 2012, 07:13:08 PM by VA3KBC » Logged
KB4QAA
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« Reply #1 on: March 28, 2012, 08:42:04 PM »

Welcome back!

Go for it!  Get them in the air.  Nothing better than having multiple antennas for instant comparison.

Strictly speaking 'Delta loops' are vertically oriented.  I would call your planned installation a triangular horizontal loop.   

Long term you might consider a multiband vertical antenna with radials such at Hygain or Hustler.  It can be very interesting to see the differences.

73, Bill
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WB6BYU
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« Reply #2 on: March 28, 2012, 09:21:50 PM »

That sounds fine.  If you prune the loop to resonant length at your favorite end
of the band you may get by with a low SWR just connecting the 4 : 1 balun at
the feedpoint and using coax the whole way.  Otherwise it shouldn't be too
difficult to tune using ladder line, and you can use it even where it isn't resonant.

You'll find that the radiation pattern breaks up in to multiple lobes on the higher
bands, so in some directions it may be better or worse than othe antennas, but
that is why you don't limit yourself to just one!
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VA3KBC
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« Reply #3 on: March 29, 2012, 03:19:12 AM »

Thanks for the encuragement guys.
Yes I plan on also putting up a verticle on the roof of my drive shed. It has a steel roof 40'x60'.
Should work great for a ground plane.
The peak is 21' high and with a tri-pod and mast I can get the verticle up to 25' to 28'.

A 20, 17. 15, 12, 10, 6 meter is what I'm thinking.

VA3KBC
Don
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WX7G
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« Reply #4 on: March 29, 2012, 04:55:21 AM »

I ran a NEC simulation and at 50' above ground the input impedance of your loop is close to 50 ohms on 160 meters. It can be fed directly with coax or thru a 1:1 balun if 160 meters is the only band of interest. If used on 160 meters only a balun is not needed because the common-mode impedance of a one wavelength loop is very high. The common-mode current on the antenna and the outside of the coaxial cable shield will be low.

If you plan to use the loop on all bands ladder line to a tuner is the lowest loss solution. A 4:1 balun and coax can work well IF the antenna is resonated right at 1.8 MHz. The harmonic multiples will fall in the 80, 40, 20, 17, and 10 meter bands and the VSWR on the coax will be low. The VSWR will be high on 30, 15, and 12 meters. 
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VA3KBC
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« Reply #5 on: March 29, 2012, 05:25:28 AM »

I was actually wanting to run the loop on 80, 40, 20. That's why the 574 length.

I have the 268' to run 160 meters.

Then again, that's just my thoughts for know Smiley

VA3KBC
Don
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AD4U
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« Reply #6 on: March 29, 2012, 05:52:32 AM »

Way back in 1975 and again in 1976, I used a full wave diamond shaped loop on 160 in the CQWWDX SSB contest.  This was when 160 meters was divided into eight 25 KHz segments with 100 watt power limit and almost nobody was on the band.  Contacts on 160 were rare.

For the contest I used a full wave loop (555 feet in circumference) supported at the bottom on top of a 90 foot tower.  At the apex was a helium weather balloon at about 350 feet.  The sides of the loop were pulled out into a diamond shape by monofilament fishing line tied off to trees.  

I realize now that the top of the antenna exceeded the 200 foot limit imposed by the FAA, but back then I was young and did not know - or did not care.  Thank goodness I did not bring down any low-flying airplanes that weekend.

I was not a contester back then, just a novice DX'er.  Any way using 100 watts from my Drake twins (one of the few HAM rigs that covered 160 back then) I did quite well in the contest.  I have QSL cards from several stations that I worked that weekend from SC.

KH6CHC in Hawaii gave me S9+20 and G3SVK in England and PA0HIP in the Netherlands each gave me S9+30.  AA4V (not his call back then) who was operating from Jamaica said I was twice as loud as any other signal on the band.  

Remember this was on 160 meters using just 100 watts.

In 25 words or less, a full wave loop on 160 meters WORKS.  Good luck with your antenna.

Dick AD4U (WB4QZT back then)
« Last Edit: March 29, 2012, 11:33:40 AM by AD4U » Logged
VA3KBC
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« Reply #7 on: March 29, 2012, 11:04:11 AM »

At the top of the picture you can see the row of trees.
The drive shed to the right.

A Cushcraft MA-6VA would work great up there on the peak.

http://www.pbase.com/djstefanik/image/101333948
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K9KJM
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« Reply #8 on: March 29, 2012, 10:27:21 PM »

I just feed mine direct with an electrical 1/4 wave length of some surplus cable tv RG6 coax (Free! from your local friendly cable installer, Ask for "spool ends") The RG 6 transitions directly to some 50 Ohm coax that runs to the radio.   Works great.  Even works on other bands through a tuner.
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