Loop-On-Ground Antenna

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by AI5DH, Aug 1, 2018.

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  1. WN6F

    WN6F Ham Member QRZ Page

    Lets not lose focus though - this is about the on ground loop.

    For SWL / ham-swl's, this can provide some unique opportunities for antenna placement with a little imagination.

    Needing no supports is obvious. Pretty stealthy. No hoa concerns. Just keep it safe so nobody trips over wires.

    For apartment / condo dwellers, where there may be no access or restrictions to the roof, or performance with a small vertical loop inside the residence is not performing well, the mere fact that this is outside and possibly away from a structure is a big advantage.

    Thoughts: if you have a small yard area, or even a common little patio shared with others, it might be possible to run a loop around the perimeter and not raise any eyebrows. On the second floor? If you can run a small coax DOWN to this little lawn area - bingo.

    Can't run coax? I've even used zip-cord in a pinch as the transmission line to the 9:1 since it isn't so critical overall. Here, I'd definitely recommend a common-mode choke on a coax transition. Don't choke the zip-cord, put that on a transition.

    If you use your imagination, the on-ground loop can provide some other options to getting your antenna *outside*, even if that means on the ground, which may perform better than anything inside.
     
    SWL37632 likes this.
  2. K3EY

    K3EY Premium Subscriber QRZ Page


    Been logging NDB’s for going on 40 years and why this thread caught my eye. Used most radios under the sun that are good for NDB’s. The FTdx10 and TS590SG are about equal for NDB’s. I only have the TS590SG now. I use a EFLW for 160 meters up 20 feet running down over the hill I live on. With that antenna I have logged beacons thousands of miles away as well as AM BC stations all over the country. Matt is an interesting experimental type guy and I’m sure these loG antennas work. That said, this is indeed interesting, but I’m not going to even try, I’m happy with what I mentioned without all the trials and errors and especially the effort.

    Good Thread hearing what others do!
     
  3. KA9MGC

    KA9MGC Premium Subscriber QRZ Page

    Just make sure to put "Vintage" in huge letters. That's the ticket with eBay.
     
    SM6CJB likes this.
  4. WN6F

    WN6F Ham Member QRZ Page

    No problem - use whatever works best for you.

    One thing worth mentioning because it might be easy to skip over if you look at KK5JY's page about it:

    Don't exceed a wavelength in circumference at the highest frequency of interest. If you do, the pattern gets all wonky and could at first seem to be quiet, but the actual lobe(s) in use are now a total joke.
     
  5. WN6F

    WN6F Ham Member QRZ Page

    Sidenote: K3EY and his EFLW antenna. Try *that* on the ground. How do you do that without it being just a complicated random wire with poor performance?

    Although I've used logs and dipole-on-ground, I have also used your typical EFHW hardware for those with just skinny lots and need to feed on the end. BUT, it needs some extra junk on the ground. :)

    Visualize:
    You've got your typical EFHW with a 9:1 auto-transformer that shares a common ground on the shelf. Put it on the ground like so:

    A) Run 40 feet of insulated wire out from your 9:1 efhw autotransformer on the ground.

    B) Put a 20 foot coax jumper on the other side of the autotransformer. Tape up the coax shells, since we are purposely going to use the common mode to be part of the antenna and you don't want the shells touching ground.

    NOTE** these lengths are not critical. Try what you have laying around.

    C) Put a physically *isolated* 1:1 transformer at the end of this jumper. Now run the rest of the feedline you need to hit the shack.

    I heartily recommended and inline common-mode-choke just past this as well.

    If this goes beyond a half-wave (wire + isolated jumper), at the highest freq of interest, then you may start getting some weird lobes. Output as compared to a loop will be a little less.

    A lot more work compared to a loop. And more junk on the ground which may not please the family. But if you have an EFHW and want to experiment and put it to use, there you go. Keep the antenna hardware taped up and not touching ground.

    So this is not a LOG, but something that I got inspired to try after using the log asking the question "what if a person only has a skinny sideyard, and no room for even a log?
     
    Last edited: Jul 13, 2021
  6. N5YPJ

    N5YPJ QRZ Moderator QRZ Page

    As stated earlier I am new to receive antennas so not disputing anyone who says that this antenna should not work, I appreciate and value the advice I have gotten here.
    That said - 40 meters is unusable for DX for me due to S-9/+10dB noise unless I have some sort of receiving antenna and I do a loop on ground and also two W6LVP loops phased with noise canceler. Some mornings I will alternate back and forth between the magnetic loops and the LoG. I have put IMO a few nice QSOs in the log including a JD1, JAs, YBs using the LoG.Likewise I have put several new ones in the log with the mag loops.
    On 17 meters noise is a toss up, sometimes it is S-3 to 5 and I will receive using the PRO-57B. Other times when noise is high I have tried the mag loops they are not really effective so I tried the LoG and put a VP8 Falkland Is in the log for a new one on 17.
    In my case I credit propagation a lot for my DX contacts but propagation can be great on 40 or 80, if I can't hear them then I can't work them. The LoG lets me hear as do the mag loops. I just wish things would go back to the nice S-3 or so noise level they were 1 1/2 yr ago!
     
  7. WN6F

    WN6F Ham Member QRZ Page

    Yep - there's no magic to it - all we're doing is playing the s/n game. If you've got some gnarly qrm locally, you'll hear it if it's strong enough.

    If you are wanting to do high-freqs, then use a small loop else your pattern will be wonky. During the last few contests, even 15m opened up for a few hours which I enjoyed using only a 45 foot circumference loop. And the transformer had cores which went higher than 10mhz. Even 10m short-skip beacons and stations were heard too.

    Just sayin - if you are still at wit's end, and you aren't using a CMC, then try one. If you get a taste with an MFJ, you'll probably want to go Balun Designs or Myantennas or similar hard core.
     
    N5YPJ likes this.
  8. N5YPJ

    N5YPJ QRZ Moderator QRZ Page

    I'm think about "pruning" mine from 60 ft to around 45 ft. From the get go I noticed my LoG did pretty good on 17 mtrs.
     
  9. N5YPJ

    N5YPJ QRZ Moderator QRZ Page

    Where do you install the CMC - feed point or shack entrance?
     
  10. WN6F

    WN6F Ham Member QRZ Page

    Meh, don't shorten it to 45 feet circumference if you only go up to 17m. The pattern still holds for the most part. Even casual visits to 15m is ok.

    But, if you really want to maintain the pattern up to 15m or even 10m (mostly short skip for me), then pruning to 45 or even 40 feet is a better deal. Of course you start to lose the output on the low bands.

    Maybe throw out a smaller loop intended for the higher bands is the way to go, but for casual use, 60 foot loop does ok at 17m too.

    (Note - EZnec makes creating loops easy - even the demo version. Put 'em 1 inch above ground. EZnec makes it easy to change sizes withought having to change each element individually. Thanks Roy - W7EL !)

    It does seem ludicrous using one of these on the high-bands, where space is not a big deal, but it is kind of mind-blowingly fun.

    I put the CMC in the shack as the last device before going out to the loop.
     
    N5YPJ likes this.

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