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Does anyone here have experience with mag Loops?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by G4SEB, Sep 6, 2020.

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  1. G4SEB

    G4SEB Ham Member QRZ Page

    Hi,
    I'm a 15 Year Old who just got their license in late May. I currently have a Xiegu G90 for HF. So far I have tried making a wire dipole which is resonant at 20m. I am using a NanoVNA to tune it, and as far as that is concerned it should work well. However, I have only managed to get one contact so far on HF. I have went on a local WebSDR and heard nothing on the frequency I was on. I am using the full 10W I can use at foundation level.

    Because of all this I am looking at getting a premade antenna. I have been looking at verticals and Magnetic Loop antennas. Magnetic Loops are the most compact solution, and I won't have the trouble about taking it up and down all the time. However, I have heard about how they aren't very good antennas, and if I am spending around £200 on an antenna, I want to get something that works well.

    Does anyone here have any experience with Mag Loops, especially on the 20m Band?
     
    KX4O likes this.
  2. WA7ARK

    WA7ARK Ham Member QRZ Page

    Comparing a 20m-band, center-fed, 1/2wl dipole at ~1/4 to 1/2wl a.g.l. to a small transmitting loop tuned to 20m, about the best you can expect is that the loop is at best 1 s-unit (-6dB) below the dipole... it might be a bit more.

    You would not likely notice that when receiving, but -6dB reduces your transmitter's 10W to 2.5W....
     
    KU3X, KD0CAC, N8TGQ and 1 other person like this.
  3. G4SEB

    G4SEB Ham Member QRZ Page

    Thanks for the reply. If that is the case I will stay away from Mag Loops. It seems a lot of money for something that doesn't perform well. I might have a look into verticals, or try and get the G5RV kit. I don't 100% know why my current antenna isn't working well. Technically it should work.
     
  4. WA7ARK

    WA7ARK Ham Member QRZ Page

    Mag loops are tiny, are easy to hide, and they sometimes help in being able to null a noise source..., so they have their place. OTOH, there is a price to be paid for those advantages.

    How high is the 20m dipole?
    How close to surrounding stuff?
    How long is the coax?
    How is the coax connected to the dipole?
     
    KL7SG, KU3X, WB5YUZ and 1 other person like this.
  5. N8TGQ

    N8TGQ Ham Member QRZ Page

    Keep trying with your dipole. Maybe you can orient it differently. Depending on how "local" your SDR is, you may be going right over it!
    Not sure if you're using CW or phone. 10 watts phone on 20 right now will be tough. Patience, persistance and timing are your best bet. Plus the sunspots are on the wayd
     
  6. AI3V

    AI3V Ham Member QRZ Page

    A "magnetic loop" will suck bullocks compared to your dipole.

    My experence is installing and operating a 32 loop array for the U.S.Navy.

    Rege

    P.S. you do have the dipole higher than the house you are operating from? ;)
     
  7. VK3YE

    VK3YE Ham Member QRZ Page

    20m can be a difficult band to get contacts with QRP. Especially during the solar low. But things will get better from now on.

    In the interim try making a 40m dipole as that's a much easier band.

    Or if you lack the space a 20m dipole with loading coils on the end to give you 40m.

    Even 80m can be easier for contacts than 20m.

    Foundation video guides on various bands here: http://home.alphalink.com.au/~parkerp/gateway/foundation.htm

    Experiences & ideas for magnetic loops here:

    http://home.alphalink.com.au/~parkerp/projant.htm
     
  8. KD0CAC

    KD0CAC Ham Member QRZ Page

    As WA7ARK asked , how high in the air ?
    The lower the more local contacts and less DX .

    What are you antenna limitations ?
    Why do you have to " trouble about taking it up and down all the time " ?

    A vertical with radials maybe easier to put up & down - if you have to .

    Either a vertical or horizontal can , in most cases , outperform the mag-loop and cost much less .
     
  9. AI5DH

    AI5DH Ham Member QRZ Page

    A mag loop has it place. A mag loop will outperform a compromised dipole. Not many can erect a proper dipole. However there are some catches and few commercial units can meet the specs. To be a true mag loop circumference be 1/10th wavelength or shorter, and extremely low resistance with precision remote capacitor tuner control. That allows you to get the very high "Q" and super narrow bandwidths. Will not outperform a properly erected dipole, but better than a compromised dipole. So they have their place.

    This is where you need to find a commercial operator with some scrap hard line, waveguide, or heliax to construct the loop, and be prepared to shell out a hundred for a good vacuum variable capacitor. Then come up with mechanical remote tuning which is kind of easy to do if you have worked with servos and step motors. A simple PWM tx is all one needs. A good commercial made unit like that will cost $700 and up. Very few exist. It is a challenging DIY project because it involves a lot of skills from fabrication, to writing code for a PWM transmitter to tune the thing remotely. Someone with either robotic or RC remote control can help with that as there is lot of code already out there.
     
    KF5KWO likes this.
  10. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    This is an important question.

    So is, which mode are you using? I know your license class limits you to 10w. That's not very much on 20m SSB. It's a little better on 20m CW, and a lot better on 20m FT 8.
     

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