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Interesting variation on a delta loop or folded dipole

Discussion in 'Amateur Radio Antennas' started by Moleculo, May 19, 2009.

  1. Moleculo

    Moleculo Administrator Staff Member

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    I stumbled across this wire antenna project today. It's an interesting variation on a cross between a folded dipole and a delta loop. The original is posted at Dual Loop 80 and 40 Meter ZZ Wave Net HF Wire Antenna Project by VE6VIS.

    One thing I'm unsure about is what the radiation pattern would look like on this antenna?




    THE ZZ "WAVE NET" ANTENNA BY VE6VIS

    A DUAL LOOP - 80 AND 40 METER HF WIRE ANTENNA PROJECT
    When you can't go out, you've gotta go up!
    Updated Sept, 2006 with new information

    Do you want a full wave loop for 80 and 40 meters but have only a city lot?
    Got a 64 foot tower or equivilant support with enough space at the top to add some insulators and a little time plus some wire? Got some 16 foot supports for each end? Want a great signal on both bands?
    Then try this antenna project submitted by Mike Wigle, VE6VIS and prepare for loads of fun!


    This antenna is the result of many hours of thinking and tweeking and trial and error and starting again and again. It was worth all the effort as I have come up with a very fine antenna that should make the lives of many hams much better by using a loop antenna instead of the inverted V's that so many of us use now.
    The antenna is basically a full wave 80 meter loop on top and a 40 meter loop on the bottom all supported from a 64 foot center support, namely my tower. They are both fed from the center feed point with one length of 50 ohm coax. No tuner is required. Use the standard formula: 1005/freqmhz, (your center frequency), for total length of each "loop". Adjust for best swr by raising or lowering feed point from top of antenna. It requires the 64 foot center support (tower or mast) and 2, 16 foot end supports. VE6VIS
    Editors note:

    Another way of looking at this project is that two Delta loops, one for each band and squashed to fit the space on the tower and your lot are paralleled and fed with one length of coax.



    The ZZ Wave Net is a revolutionary
    new design in HF antenna's.
    The ZZ Wave Net starts with
    the same principal as a dipole
    antenna bent into an inverted V
    .​
    [​IMG]
    Next, the ZZ is a folded dipole bent
    into an inverted V loop!!!



    [​IMG]
    Next we pull the ends of the folded dipole and separate
    the middle as in the drawing above.
    This allows us to install the antenna in a city lot and still
    keep the overall performance of a full wave loop antenna!

    Then we add the 40 meter ZZ loop under the 80 and we have the ZZ Wave Net, a dual 40 & 80 meter full wave loop antenna!

    Below is how it looks installed on a 64 foot tower with 16 foot
    end supports on your city lot.


    [​IMG]

    [​IMG]
    Dimensions:
    (80 meter on top, 40 meter on bottom)


    80 meter apex to end 70 feet
    80 meter end to feedpoint 65 feet
    40 meter feedpoint to end 36 feet
    40 meter end to bottom 34 feet

    Apex to feedpoint 24 feet
    Feedpoint to bottom 12 feet

    Feedpoint is 4:1 balun
    Both loops feed from this point
    End support to end support 105 feet

    Construction:
    Measure wire and lay out at base of tower.
    Attach 1 litre bottle half full of water to the bottom wire about 12 feet from the ends on both sides of antenna.This is so the wires don't twist and so the antenna will have greater tuning range.
    Attach apex of antenna to top of tower on a standoff and preferably with a rope and pulley system.
    Pull feedpoint up to 24 feet below apex.
    Pull ends out to look like the picture
    .

    Tuning Instructions
    The wire length is the first thing to get right.
    Use the usual method of (low longer) ie: if the swr is higher on the low freq then make the antenna longer and if the swr is higher on the high side then make the antenna shorter.
    Then the next step is the distance between the wires.
    The distance between the feed point and the apex is 24 feet @ 80 meters.
    The final tuning is done by tightening the wires from the ends.

    [​IMG]
    Loose ZZ


    [​IMG]
    Tight ZZ


    So you get the antenna pulled out to look like the
    picture above, then you can adjust the swr by tightening and
    loosening the wires. You will see a great range of
    tuning here which is why this antenna design is so
    easy to tune.

    The best way to do this is to mark the place where the
    rope meets the tie off point. ( this is the trick for
    tuning this antenna) So, if for instance you have the
    rope tied off to a tree. You mark the point where the
    rope meets the tree by tying a piece of string onto the rope.
    This is your marker.

    Check the swr. Then loosen the rope so the marker is
    about a foot from the tree, Then check the match again. You
    will notice that it has changed. Now you can tune to a
    point where the match is lowest.
    Shorten and lengthen the wire to provide the lowest swr
    within the range that you can loosen and tighten the wires
    for lowest swr and you will find that this antenna will
    match right down flat at the operating freq of your choice :)
    Also you may find that the antenna wants to be shorter
    than the normal calculation.This depends on a number of factors
    like reflections and hieght above ground.

    Tune the 80 meter length first and then the 40.
    This antenna also works as an 80 and 20 or 80 stand alone,
    40 stand alone, 40 and 20 etc.

    Have fun :) Mike Wigle, VE6VIS


     
    #1
  2. HomerBB

    HomerBB Well-Known Member

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    Where as I'm not licensed to ham, so limited to CB, posting something like this is a dangerous thing where I'm concerned. I start thinking, "...how can I do this in my situation..."

    I may be incurable, and this don't help :)
     
    #2
  3. Captain Kilowatt

    Captain Kilowatt Professional Amateur Staff Member

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    I see signal cancelation happening everywhere.
     
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  4. HomerBB

    HomerBB Well-Known Member

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    I see wife cancellation everywhere if I try it
     
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  5. W5LZ

    W5LZ Crotchety Old Bastard

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    The only real similarity that a full wave loop and a folded dipole have in common is that they are a 'closed' loop, there are variations make the two seem sort of 'related' in a way. If you start with a folded dipole, and sort of start increasing the area inside that loop that it makes, it varies it's characteristics. As that area inside the loop get's larger, the feed point impedance starts to decrease. So, starting at about 300 ohms, it decreases till it's something close to 100-120 ohms (the full wave loop). That's handy in one way because you can get that input impedance to a manageable point such as a 3:1 and use a balun to feed the thing. It's also 'un-handy' because it changes it's radiation characteristics to something that isn't typical of either a dipole or a loop. If that radiation pattern fits your situation, that's good! If not, then it's bad.
    These particular antennas can be handy because they might fit where you have space to put them. But, you're back to the radiation pattern thingy, does it put a signal in a usable place for you? then again, if it's a choice between a not very usable signal and no signal at all, I'd probably take the not very useful signal antenna, wouldn't you? And of course, that's sort of like feeding a dummy load legal limit power and signing your self as being QRP. Hey, it's better than nothing!
    As far as getting an input impedance close to 50 ohms, you can do that by manipulating the shape of a lot of different antennas. Using that "angle of the dangle" with dipoles has been around for ever, for instance.
    Oh well, I think playing with antennas is fun. Something like these two may come in handy some day, who knows?
    - 'Doc
     
    #5
  6. W5LZ

    W5LZ Crotchety Old Bastard

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    HomerBB,
    No guts, no glory! Then again, no meals either...
    - 'doc
     
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  7. HomerBB

    HomerBB Well-Known Member

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    I do like to eat
     
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  8. zzwavenet

    zzwavenet Member

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    ZZwavenet antenna

    Hello and thankyou for posting my antenna.
    the reason the antenna is "squashed" like it is, is to make it 200 ohms.
    a delta loop is about 150 ohms.
    by squashing the antenna we drive the impedance up.
    I now run this antenna as a 300 ohm antenna squashed even closer together.
    I use a 1.5 to 1 unun (unbalanced to unbalanced) into a 4 to 1 balun to get the 300 ohms and run ladder line out to the antenna. this is much better as the ladder line has a fraction of the loss the coax has.
    It is 200 feet from my shack to the tower so line loss is a significant challenge.
    ttys Mike
     
    #8
  9. mackmobile43

    mackmobile43 Jock Supporter

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    I do all my work of the roof, that way she can't stop me unless she calls the fire department to come and get me.
     
    #9
  10. HomerBB

    HomerBB Well-Known Member

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    She's good at withholding er, uh . . . meals. And, she a dead shot with rock chunking.
     
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