Wall Loop 20m.

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by PD7MAA, Feb 15, 2016.

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  1. DB9MAT

    DB9MAT Ham Member QRZ Page

    Wow. Just finished the Wall Loop and got Italy (about 1500kms) after just one call. With 3.5 Watts. So yeah, maybe this loop is not ideal, but it definitely works and is way better than nothing! :)
     
  2. SP3L

    SP3L Ham Member QRZ Page

    And what capacitance did you use?
     
  3. DB9MAT

    DB9MAT Ham Member QRZ Page

    150pF. Didn't play with other values yet, SWR is about 1:1.2
     
  4. K8JD

    K8JD Ham Member QRZ Page

    If your walls were 16 ft high, you could put up two loops on opposite sides of the house and have a cubical QUAD directional antenna !
     
    KM4OYP likes this.
  5. SP3L

    SP3L Ham Member QRZ Page

    Nice try. :)
    Unfortunately, a magnetic loop radiates in quite different direction than a full wavelength square loop used in the cubical quad. See the picture below.

    upload_2016-3-21_22-58-46.png
     
    KM4OYP and NH7RO like this.
  6. PD7MAA

    PD7MAA Ham Member QRZ Page

    Hi Jacec

    It's clear that the wall absorbs a part of the hf power but that's common with indoor antennas. Another downside could be the indoor noise detection.
    The capacity of the wall does clearly add to the bandwidth .
    There are no wonder antenna's but the simple, effective and cheap concept of the wall loop make's it hard to beat
     
  7. SP3L

    SP3L Ham Member QRZ Page

    Absolutely.
    A friend of mine, a good DX-er, is just collecting materials to build a copy of your antenna for 21 MHz band. We all new that this will not be as good as an outdoor dipole but you do not even have to go out to build this antenna and start using it.
    So, thanks for sharing your idea!

    BTW, have you tried to put it on the ceiling? Simulations show that it should be then almost perfectly omnidirectional - like a GP. Assuming your XYL does not protest too much of course...
     
  8. SP3L

    SP3L Ham Member QRZ Page

    Sorry for the typo. It should be: "We all know..."
     
  9. PD7MAA

    PD7MAA Ham Member QRZ Page

    The vertical position was chosen to limit the indoor noise and to radiate as much as possible power towards the window.
    A ceiling mount could be a nice solution for the attic.
    Yes , my xyl keeps a sharp eye on my projects :)

    73 John
     
  10. SP3L

    SP3L Ham Member QRZ Page

    My friend, Stan - SP3BGD, has repeated your design, John. Please find below a few photos of his version of PD7MAA Magnetic Loop.

    upload_2016-3-25_9-20-46.png

    upload_2016-3-25_9-21-8.png

    upload_2016-3-25_9-21-42.png

    SWR min. ca 1.5:1.
    The first two QSOs: UE2KF and I8GMG in digital modes at 30 W output. RST: 559.
    No TVI even at 100 W output.
    For the 14 MHz band, the twisted wires have 7 turns on 19 cm.

    Stan successfully re-tuned the antenna to the other bands (18 and 21 MHz) by reducing the number of turns in the top capacitor - see the photo below. He got SWR=1.7.

    upload_2016-3-25_9-26-40.png

    The experimental antenna has been de-installed due to Easter holidays. But Stan is going to coninue with it when the holidays are over..
     

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