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Directional AM loop/antenna?

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  • Directional AM loop/antenna?

    Hey, not that I DX AM at home nearly as much as FM/TV, but something I wanna know.

    Is there a reasonably priced antenna or loop for AM, that gets stations from only one direction, when oriented? All I have are the small portable 2-way loops (you know---north/south, northwest/southeast, etc.).

    I know they exist, because I was at someone's house and saw it in action. Does one have to be built?

    I have no clue how to build such things. No idea where to put a capacitor, how many turns to make...whatever.

    Something tells me that these already-made antennas will run me over $600 or so. That is definitely out of the question....on top of that, this house is subject to noise. Are there portable or battery-operated antennas like that?

    I do enjoy hearing Caribbean/South America stuff pre-sunset, but there is a decent daily window of only about 30 minutes---so I have to make the most of it.

    Any help would be appreciated.

    cd

  • #2
    I have a small loop I use to catch AM DX from the south. It's outside. The vertical sections are 10 feet tall, the horizontal sides are 25 feet long. You can do a 6 foot by 9 foot loop if you want but a small loop like that won't have much gain and you'd need to run it into a preamp, then to your receiver. The uprights are just a couple of cheap aluminum poles. The side you connect the coax to (or speaker wire, in my case) is the end you want to aim at your DX direction. On the other end is a 1000 ohm resistor that you adjust to get your null in the opposite direction (if you aim the loop south, the resistor adjusts the nulll of stations to your north. So the loop will be directional. On the side where you connect your coax or speaker wire, you need a toroid. These are very inexpensive...a dollar or two. Put a few loops around the toroid and connect the ends to your speaker wire. Run some turns around the toroid again and connect the ends to the bottom and top vertical wires. I forget how many turns but play with it using different amounts of turns. You can find this info online. Hope this helps.
    Mike B.
    Enfield, CT
    -72° 30' W/41° 59' N
    FN31RX

    Online since 1999 and still going at
    mikesdx.com

    Archives: The Original Mike's TV/FM Page with Tuner Mods and Lots of Old Stuff

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    • #3
      I guess it does, Mike, but I couldn't construct one of these for the life of me. I do know some AM DXers around the world, who could certainly figure things out better than I. Thanks.

      cd

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      • #4
        There's likely nothing you can buy to fit what you've described. A pre-amplifier could improve the performance of a smaller loop. For our DXpeditions we use 16' (v) x 36' (h) loops. To get a unidirectional pattern requires, as Mike has said, a resistor. Unfortunately, it's difficult to knock down the signals from, say, the South to get those from the North. There will always be some bi-directionality. There are plenty of places on the web where specs for the toroid can be found. That goes toward the feedline end of the loop, which is usually opposite the resistor. A pre-amp would come on the feedline, preferably inside. A pre-amp is going to run a few hundred dollars.
        Russ Edmunds
        15 mi NW Philadelphia, PA
        WB2BJH -- Grid FN20id

        2 ) SDRPlay RSP1a SDRs, Onkyo T450RDS,
        Yamaha T-80 & Conrad RDS Manager;
        Yamaha T-85 & Conrad RDS Manager;
        all w APS9B @ 15'
        Insignia NSHDRAD2 w/ whip.

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        • #5
          Since we already have a topic on this. I will be ordering an MLA30 loop from ebay (~$40). Owners say it rivals amplified loops that cost 10 times more. Once I get it I will share feedback.
          Ivan NO2CW

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          • #6
            Yes, this will be interesting to hear!

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            • #7
              Reviews of the Low Cost MLA-30 Wide Band HF Magnetic Loop Antenna

              https://www.rtl-sdr.com/reviews-of-t...-loop-antenna/

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              • #8
                It seems to me that if one has to provide all of the hardware, and assemble it, that's only one step removed from home-brewing the whole thing. And if it's as low on gain as some of the reports indicate, then one or more amplifiers will be required, and that involves some cost. I haven't seen/tested one of these, and I'm not saying it's a bad antenna. I'm just making a couple of obvious points. I've seen and used a home-brewed imitation Wellbrook loop which performs quite well using amplification similar to the Wellbrook, which is another way to go.
                Russ Edmunds
                15 mi NW Philadelphia, PA
                WB2BJH -- Grid FN20id

                2 ) SDRPlay RSP1a SDRs, Onkyo T450RDS,
                Yamaha T-80 & Conrad RDS Manager;
                Yamaha T-85 & Conrad RDS Manager;
                all w APS9B @ 15'
                Insignia NSHDRAD2 w/ whip.

                Comment

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