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Thread: Very Long Horizontal Loop

  1. #1

    Default Very Long Horizontal Loop

    Hi Folks,

    Virtually every article written about horizontal loops suggest "Bigger, The Better" as its performance depends upon maximum enclosed area. With 18 acres to burn, that statement is compelling.

    But, it seems at some point one would reap diminishing returns (at least from resistive losses of the wire, itself).

    Does anyone have any experience or thoughts?

    Thanks,

    John

  2. #2
    Super Moderator 5B4AJB's Avatar
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    I would consider a wire beam if you have that much space, albeit fixed, a 3 element fullsize yagi is hard to beat...

  3. #3

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    HAAT is another factor, unless all you want to do is heat clouds. Plus, the more length you go compared to wavelength you are operating on, the higher that ratio gets the more weird, unpredictable your lobes will get. Which can present its own set of operational problems, especially with unwanted nulls.

    Better to stick to full wave loops IMO. Easier and less costly that way too, unless budget is no concern.
    In which case you have bigger problems than can be properly addressed here.

  4. #4

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    I've had good luck with my horizontal loop. It was intended to be a full wave on 80m, but I had to add wire to get it up through the limbs in the pine trees. It ended up being about 350 feet long, and it's up 60 feet. It's fed with home brew open-wire line which leads to a 4:1 current balun, which is followed by 15 feet of RG8X to the tuner in the shack.

    I assume it has some funny lobes and nulls, but it's been a good antenna. I worked VP6D with it on all bands 10m through 80m on CW at 100 watts. Since I got back on the air in February 2018 after 10 years QRT, I've worked 156 DXCC countries, most of those on the loop. My other antennas are an old Carolina Windom, 10m-40m, up about 70 feet, and an inverted L for 160m, which was put up in December 2018.

    With 18 acres and some decent trees, you should try a full wave on 160 fed with some open-wire line.

    I have QSOd with a couple of operators who had 1,000-foot loops, but I've not heard of any that are longer than that.

    It is a good DX antenna on 10m through 40m and fair on 80m. From my QTH in central Louisiana, I've worked (and confirmed) Japan and Samoa to the west, Corsica, Belarus, and Greece to the east and Argentina to the south on 80m, all on CW with 100 watts.

    My loop and feed line are constructed from #14 THHN stranded wire from Home Depot.

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    I had a horizontal loop similar to JohnD. I made a computer model before I put it up which guided me to how much ladder line to drop for the feed. The total loop was probably ~270' & the dropped ladder line was ~25' also to a 4:1 balun and 8' RG8 mostly coiled. With an autotuner I could almost get to the bottom of 80meters. Some days better than others. It could have used a bit more wire but I had used up all available space as it was. On the other hand, all HF bands were available.

    I used The Wire Mans 13 AWG (yes, it is a thing) copper clad plus thier rope that is slightly larger. Both over kill but I like that rope size. That rope works well with HD 4" plastic clothes line pulleys. Yes, I studied what pulleys to use a lot. The guys buying pulleys sailor use have a strong argument but cost more than made sense to me. (My future wire antennas will use that THHN wire from HD for further savings, BTW). I justified the plastic pulleys by realizing how heavy a fully loaded clothes line is (== very heavy!! and antenna even under tension is much less). Critical dimension of the pulleys are whether or not the rope or the wire can slip out of the groove == big PITA.

    Last, the open wire line I made use the ends of the loop for lack of a better description. The spreaders are 1/4" PEX but are PITA to cut even with the PEX cutting tool although they are very durable and seem unaffected by UV. The next spreaders that will be tried will be irrigation tubing of about the same diameter. Both are very ham budget freiendly. Black TyWraps are shoved in from opposite ends of the tubing, the free ends are wrapped around the wire and then secured in the locking head of the opposite TyWrap. A challenge with this are getting the TyWrap tight enough so the spreader does not slip on the wire. Next time will probably use a small dab of weak adhesive. The distance between the spreaders were ~3' & not critical. I used 3' of the rope with wire clamps (from HD in the clothes line area) to hold the antenna together just above the top spreaders.

    Other antennas for the higher HF bands might work better with directionality & all that, but with a SDR that works all HF bands plus waterfall it was excellent for jumping nearly instantly from one band to the next going from 80m to 10m was a couple of seconds.
    -Jeff NE1U

  6. #6

    Default Thanks

    Thanks to all that replied.

    Modeling on EZNEC showed no improvement on Top Band by making a loop larger than 1 wavelength at 160. After some thought as to why this was so, it occurred to me that at 70 - 80', it is still a sky burner. The very large loop presented many more lobes at 10 meters, which filled-in the nulls, but shifted the deep nulls lower - making 40 meters unpredictable.

    I also reasoned that the ohmic losses of a very large loop would defeat any benefit in gain I might enjoy. Then there are the near field ground losses...

    Sometimes it pays to lay out a question even if it is absurd. For now, I will do a full wavelength on 160 and Be happy with the sky-burner on that band.

    Thanks again,

    John, N9RF

  7. #7

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    18 acres? Get some two-by-fours, erect a few really tall masts and suspend a large vertical loop. Or six masts spaced per yagi specs and hang a dipole in the middle and a reflector and a director. Wire is cheap.

    Kraus
    Last edited by KC4ZGP; Mon 7th Jan 2019 at 19:48.

  8. #8

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    Not sure what Top Band means, but for Ohmic resistance a 1000' #13 is ~2 Ohms ... at 68 deg F

    Yes, for 160m it would have to be at least 130'.

    There were plenty of nulls predicted off my loop for any band. Didn't matter to me as I just wanted some -- thing that was usable for most of HF and I did have DX on most of the bands when they were open. I was also planning a relay on the side opposite the feed and possibly adding a wire drop of some kind. Unfortunately one of my supports relied on one fiberglass 4' tent pole at the top of ten aluminum poles ... and we are moving so all of that will saved for another day. I haven't even bothered modeling the "expansion" as this install is very site specific and therefore have no idea if my notions are just wild ideas. But, modeling will lead the way when the opportunity arises.
    -Jeff NE1U

  9. #9

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    Something else to consider - think about putting a wire reflector loop on the ground under your horizontal loop for a bit of gain here and there, at least in the NVIS type of reflection. Lots of stuff on the web about NVIS.

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