Loop On Ground Antenna

Discussion in 'Amateur Radio News' started by KD5W, Jul 18, 2021.

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  1. W1YW

    W1YW Ham Member QRZ Page

    Any poor antenna can succeed as 'receiver only'. It succeeds (mostly but not only)by channeling out-spatially-- areas where noise may predominate for the (nominal) TX antenna--if you have enough detectable signal to start.

    Obviously of you attempted the same ability to spatially channel on the TX antenna, it would have that same advantage on receive.

    Much of today's man made interference seems to predominate at high angles, which is why monopoles (which have a suck out at high angles) often work well for noise mitigation.

    Even if you get a loop somewhat off the ground (at least a few feet) it will curtail some of the 'transmission line phase cancellation effect' AND start into a NVIS regime. IF the noise is high angle on receive, you can combine that and the TX antenna (on receive), phase them, and do a pretty good job of phasing out the noise. Not always, but often.

    Phasing up a couple of very small loops--inside -- is a RX good solution in an HOA environment--as long as marijuana grow lamps don't predominate as the noise source.
     
    Last edited: Jul 22, 2021
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  2. KM1H

    KM1H Ham Member QRZ Page

    So why do BOGs work so well? Granted not everybody can run them 100-250' or so but loading coils work and most radios have way too much gain on the low bands that an external preamp isnt necessary
     
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  3. W1YW

    W1YW Ham Member QRZ Page

    Beverages work because there is a discontinuity of the wave at the boundary. That creates a directionality which channels out noise at other angles.

    For LOG's--

    Laying the antenna on the ground....and the transmission line effect...

    Because ground is not 'ground' to RF. Depending on the composition, different 'grounds' have an effective height above the boundary condition layer for some frequencies.

    If the ground is a copper sheet then the boundary condition is the copper sheet. If the ground is a layer of muck , granite, sand, organics, the 'ground' is approximately a lossy substrate with a nebulously defined boundary layer below it. Sometimes that is inches, sometimes feet. Depends on your 'ground' composition and the frequency.

    73
    Chip W1YW
     
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  4. UT7UX

    UT7UX Ham Member QRZ Page

    Nathan, I apologize. Having being non-native English-speaking person I often feel difficulties to explain sarcasm as clear as it could be understood by almost everyone while remaining hmm... sarcastic?
     
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  5. K9WW

    K9WW Ham Member QRZ Page

    Please note that the author is comparing the LOG outside to a dipole in his attic. Apples and oranges.

    Kirk K9WW
     
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  6. UT7UX

    UT7UX Ham Member QRZ Page

    On lowest bands especially where only SNR matters. On higher bands receiver's sensitivity may not be enough to 'pull' signal that is too weak.

    Paradoxically vertical monopoles are easier to build for lowest bands than dipole-sized horizontal antennas. Sure generic HAM cannot build self-supporting tower of 130 feet to serve as full size quarter wave on 160m. Meanwhile some 30 feet or even less (with appropriate matching, sure) are much more real for most. In terms of long-range efficiency that kind of (very) short monopoles outperforms low hanged (i.e. below quarter wave above the ground) full-size dipoles. Only extreme care should be taken of the ground as ground losses are most significant losses with electrically short monopole.

    True. NVIS may be desired for some amateur application like almost local ragchewing, packet nets, and so on, but obviously not for DX'ng.
     
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  7. WB0DVM

    WB0DVM Ham Member QRZ Page

    NØTBH did the same thing to my 80-40 dipole last year after it got blown down. I yelled "Fer cripes sake, are you blind AND dumb??"

    And then OUT LOUD I said, "Don't worry about it dear - copper weld is cheap,". I mean, what were my options? Cook for myself? Sleep on the couch? I already have 911 on speed-dial.
     
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  8. KD5W

    KD5W Ham Member QRZ Page

    Absolutely true. My dipole 20ft in the air, outside would smoke the LOG. And the beverage I had at my last house would beat the dipole some of the times. But on a deed restricted lot I cannot put my trusty dipole in the air so I am experimenting with various antennas that can be hidden to the HOA prying eyes.

    I honestly don't think I will find anything better for my HOA situation than my trusted Terminated folded dipole(receive only) hidden in the attic so when I try another antenna I do compare it to the dipole. Is it a fair comparison of antennas? Probably not, but it is a fair comparison of which one works best for my situation. Since many hams are living in HOA restricted homes they want to know what their options are and what they should try. I hope my videos gives them a starting point or at least shows them options they might have not thought about. Real world application should always be more valuable.
     
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  9. NR1R

    NR1R Ham Member QRZ Page

    i made my log 140 ft of wire in a rectangle buried just below sod i am using a h/b transformer 4 turn pri 12 turn secondary 2 ferrite cores superglued together .
     
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  10. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    No. It's 20ft Inside Your Attic.

    When making claims about antenna performance one must be careful to be accurate and specific in describing the antennas and their location.

    We see this over and over again, where people start raving about the performance of some oddball, or known low performing antenna without direct comparisons, comparisons against other poor designed or poorly installed antenna, or without accurate description.

    I'm glad you are getting improvements over your attic antenna. I may try it sometime. 73, bill.

    p.s. I'm unsure what efforts you have made to eliminate Common Mode Current on your attic antenna.
     
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