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Big Loops. What is the point of diminishing returns?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by K0MBT, Nov 30, 2018.

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  1. N5CM

    N5CM Ham Member QRZ Page

    My loop is small potatoes, 350 feet, up 60 feet, compared to yours. It is fed with home brew ladder line to a 4:1 current balun then 15 feet RG8X to tuner in shack. Rig is 100 watts. I worked Ducie Island (confirmed on LoTW) on 10m, 12m, 15m, 17m, 20m, 30m, 40m, and 80m with one antenna, the loop, and 100W on CW. Best confirmed DX so far on 40m is VK9XT, 10,588 miles from my QTH.

    I'd say use your 1,000-foot loop for a few months and get some data on how it performs.
    NE1U likes this.
  2. AA7QQ

    AA7QQ Ham Member QRZ Page

    1800' of horse fence (Copper clad steel) with 450' of dual RG6 quad shield as balanced line. I was doing great in the Weatern US (Was in Kanab, UT). Slamming the east coast on 15-80. Hitting Europe & eastern Africa, too.
    Secret was being on #30 ground & 1/2 surrounded (From the west) by 2000' sheer cliffs of #30 ground.
    It surely was a 5' high cloud warmer, but got to a lot of other places, too.
    Sometimes, Geology can surely affect your pattern.

  3. K0MBT

    K0MBT Ham Member QRZ Page

    Thanks to those who shared their thoughts on this. We have always done better to the east here as we are about 75' above a plain which extends a half mile to the east and south.

    This afternoon I added a 150' to catch a better tree to the northwest side of the antenna. In effect making it more rectangular.

    Attached Files:

    Last edited: Dec 2, 2018
  4. WA7F

    WA7F Premium Subscriber QRZ Page

    Has anyone fabricated a loop in a clothesline fashion? That is, with pulleys at each corner to allow adjustment of the feedpoint position. It seems like the lobes and nulls could be useful.
  5. K0MBT

    K0MBT Ham Member QRZ Page

    Well my loop antenna took a setback last month. The 25 pound test 20 gauge insulated copper wire came down with wind and ice. Prior to that we had expanded it to about 1300ft.

    Last week my wife (n0bex) and I restored it making the north end 20 ft higher. We changed the wire to common 14g galvanized electric fence. I thought for sure that the bare wire would be grounded at least partially to the tops of the trees and that the wire's impedance would hurt the performance.

    The loop is still terminated with a 4:1 current balun and rg213.then run through a manual T tuner. I drive it with a 10 watt radio mainly with ssb.

    Certainly the performance is not diminished but quieter and am getting out better, lots of 59 signal reports.

    At this point we are talking about a 2500 ft or so loop.
    NE1U likes this.
  6. AA5MT

    AA5MT Ham Member QRZ Page

    I talked with a VOA official, who told me a story about the cold war. VOA was the only outside station to be heard in downtown Moscow, due to jamming. The transmitter was in Turkey on 80 meters. It ran 10 MW into a rombic which was 15 miles around. Very very directional.

  7. AA7EJ

    AA7EJ Ham Member QRZ Page

    I had about 600 feet loop strung between trees.
    Made from telephone "drop wire " - twin copper clad steel. Lasted years until I moved to TX.
    Yes, it had nulls and lobes and I never knew what I was going to get.
    Had a 3 way between WWA , Sweden and "windiest place on earth " station in South pole.
    The "problem" with "resonant loop " most people do not realize - it is better to be build as "subharmonic " - twice size of resonant frequency.
    The other "problem " are blackberry bushes during installation !

    73 Shirley
    Last edited: Mar 4, 2019
  8. W1VT

    W1VT Ham Member QRZ Page

    Has someone found a clever way to move those peaks around to aim at a needed DX station?
  9. AA5CT

    AA5CT Ham Member QRZ Page

    Yes: Change frequency. Lobes will shift.

    You do offer a good question though, into an area not explored yet, for instance, inductance could be switched in (IN the antenna wire itself), changing where the 'standing wave' voltage loops and nodes appear.
  10. K0MBT

    K0MBT Ham Member QRZ Page

    Here is the current antenna.

    Impressive voa station, 15 miles of antenna.

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