No room for 160m? Maybe you have!

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by MW1CFN, Nov 17, 2019.

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  1. MW1CFN

    MW1CFN Ham Member QRZ Page

    Well, a rainy day brought me back to thoughts of antennas for 160m.

    Version one was a folded vertical, in an inv-L configuration, made simply of two sides of 300-ohm twin joined together. Worked fine.

    Version two was - wait for the criticism, the naysayers, the abusers - an earth loop ('ground spike') antenna.
    Well, bring on the abuse, because I've certainly never seen such strong signals at low frequency before, and certainly haven't got a 35W signal across 10,000km to JA at 160m before.

    https://mw1cfnradio.blogspot.com/2019/11/earth-loop-antenna-experiments.html

    Then again, save the abuse, and have a go at it yourself. After all, it's just a balun, two copper tubes in the ground, and a coax feed.

    *Terms and conditions apply: ground characteristics may affect any given ground antenna's performance. If you want to deny the antenna's performance, you always have the option not to respond, read something else, and/or use an alternative antenna.
     
    PY2RAF, N0TZU, 2E0CIT and 2 others like this.
  2. AA7QQ

    AA7QQ Ham Member QRZ Page

    Well, let's hear some details. I have some wire, torroids & some copper pipe. Worth a shot.

    Ed
     
  3. MW1CFN

    MW1CFN Ham Member QRZ Page

  4. AA7QQ

    AA7QQ Ham Member QRZ Page

    I was reading that. Did you use a tuner?
    50 ohm feedline or twinlead?
    Would you think that at 15 meters separation that 80 meters would work?
    What was the reasonibg for a 6:1 balun (Was it in stock or did you experiment)?
    What material was the balun?
    Was the wire suspended from the ground?
    If too long, can the stakes (How long) just be moved inward, or do the wires need to be shortened?
    What wire gauge did you use (I have #16AWG to #2AWG)?
    I have junk & a hammer. I am ready to go.
    Not to sound this way, but do you think it is a transmitting dummy load? I doubt this, but it will be brought up.

    Thank you,
    Ed
     
    NH7RO likes this.
  5. KF5PAL

    KF5PAL Ham Member QRZ Page

    I have recently installed a L.O.G. (Loop on ground) antenna as a Rx only antenna for my RSP1A and from 80m to 20m and MW it works VERY well. received signal is lower but, so is received noise and the SNR is great. Give us the details on your setup and we will try. As above, are the connecting wires in, on or above the ground?
     
    MW1CFN likes this.
  6. K4SAV

    K4SAV Ham Member QRZ Page

    Not enough detail to understand what you have. How high is the loop? The diagram appears to show it well UNDER the ground, which I suspect is wrong. It isn't even clear if there is a loop. Is the loop just the path thru the soil, or is it a wire? How high is the other wire that connects to the two ends of the loop? How long are the ground rods?

    Jerry, K4SAV
     
  7. MW1CFN

    MW1CFN Ham Member QRZ Page

    It's a current loop, not a wire loop. Wire is just laid over bushes, no scheme. Rods are about a foot - 18 inches in the ground.
     
    Last edited: Nov 17, 2019
  8. MW1CFN

    MW1CFN Ham Member QRZ Page

    No connecting wires. The 'loop' is not a physical wire, but a 'virtual' loop of current flow. Good job on the L.o.G. antenna! DP0GVN uses a dipole on the ground (ice!)
     
  9. KF5PAL

    KF5PAL Ham Member QRZ Page

    I get that the Line under the ground is not a physical wire but, the current path. I was asking about the 2 from the coax on the top of the ground?
     
  10. MW1CFN

    MW1CFN Ham Member QRZ Page

    Hi Ed,

    Feedline to the balun is 50 Ohm coax. Yes, a manual tuner is used.
    I would guess a 15 metre separation would give you 80m operation, though it may depend on soil characteristics. I'm on extremely conductive ground (old copper mine, but the conducitiviy is mediated by FE2+ iron (highly acidic conditions)).
    No reason for the 6:1 balun; just a stock. 4:1 or 1:1 likely to work just as well.
    Wire from balun to probes is only laid over plants for the most part, so a few inches above ground, generally. Others seem to suspend the wire.
    The stakes can be moved about. The feed wires probably don't need shortening.
    I used ~1mm audio cable for the balun-stake wires, as this is much cheaper than most 'ham-specific' wire.
    Is it a transmitting dummy load? Well, I've presented my experience, of getting a decent FT8 signal across 10,000km, and will leave it for others to make their own judgement. I have given it a go, and found it to yield results that are at least worth looking into. Perhaps on certain soil/bedrock types, it will be less effective, or ineffective.
     
    Last edited: Nov 17, 2019
    NH7RO and AA7QQ like this.

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