Tune a Magnetic Loop Antenna remotely using WiFi

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N6JJ, Jun 6, 2021.

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  1. N6JJ

    N6JJ Ham Member QRZ Page

    I created a video, that will show you how you can control a Stepper Motor remotely, using WiFi, from your phone, and with that feature, you will be able to tune a Magnetic Loop Antenna remotely.

    N0TZU, K2CAJ, WJ4U and 4 others like this.
  2. K4PP

    K4PP Ham Member QRZ Page

    I very much like the use of stepper motors for loop tuning as well. How will you get the remote power to the driver/controller..bias Tee, battery with solar charger?
    I have been working a code with step counter and reference position so that memories can be used to drive to position. I Haven't got it working yet.

    PU2OZT likes this.
  3. KK4NSF

    KK4NSF Ham Member QRZ Page

    if you are using a radio with an waterfall, there are simpler ways to tune them..... since you can see the peak tuning in real time. I use a DPDT switch, and a small DC gearmotor, and can tune mine in ~10 seconds or so. For the life of me, I don't understand the benefit of controling everything from my cell phone, especially when there are more effective / less complicated/ more reliable ways to do things.
    K0UO, KC8QVO and AK5B like this.
  4. K4PP

    K4PP Ham Member QRZ Page

    The benefit for me would be that only a coax cable for antenna connection is run and everything else sits at the loop. No waterfall here but I use an swr meter. I used a stepper motor simply because of the ability to position without feedback (no meters, no position sensors, etc.) if it were something I wanted to try. I used a vacuum variable capacitor and two limit switches at each end of the range. I was hoping run the range and note my favorite spots, count the steps, reference off one switch. Maybe add a frequency/step curve.

  5. AK5B

    AK5B Ham Member QRZ Page

    I do the same with one of mine even though I have had a NEMA 23 stepper still sitting in its packaging for several years. If they ever develop a simpler, off-the-shelf way to set one of these up I may try it---but all that computer stuff is a huge turn-off for me. The last thing I'd ever want is having to use a cell phone to be able to play radio or tune my loop. I love watching my panadapter as I tune; it's like watching an RF tsunami build slowly, finally cresting at resonance. ;):)

    Thanks anyway for posting the video and I wish you all the best with your loop(s). Ever tried using a vacuum variable instead of an air cap? The only way to go, in my opinion.


    Last edited: Jun 7, 2021
    PU2OZT and KK4NSF like this.
  6. N6JJ

    N6JJ Ham Member QRZ Page

    As for power - I did designed that to be operate in the field as well, so currently, I'm just using a battery, even when i'm testing that in my garage or put the antenna on the balcony. I do have a plan to use that antenna in the coming field day with that battery.
    If it will be a permanent setup, of course that a tiny power supply will work great, it's only use ~0.4A (with my setup).

    I thought about position monitoring, means some way to track and count the steps, but it's not the best way to monitor that, because we will need to re-set that counter very often. There are some parts that may be added that can help here. I didn't spent the time yet on that.
    Maybe in the future.
    K4PP likes this.
  7. N6JJ

    N6JJ Ham Member QRZ Page

    Here as well, my idea was to be able to tune without the need to run more cables outside, only the Coax. Also, for field operation, I will not need more set of cables. I'm free to set the Antenna anywhere I want and I have the option to tune.
    I have an idea to convert the App to a simple webpage. I will do that soon and post a new video on how that looks like.
    PU2OZT and K4PP like this.
  8. N6JJ

    N6JJ Ham Member QRZ Page

    Yeah, I thought about it as well. It should be easy as the microcontroller has Analog inputs, and I can use one to get the signal from some "sensor" near/inside that loop, so then, the controller will know exactly when to stop the tune.
    That will be the next project ;)
  9. K1VT

    K1VT XML Subscriber QRZ Page

    I enjoyed your video. Please tell me if you have show notes available with details on the system and software. Thanks.

    Jack K1VT
  10. N6JJ

    N6JJ Ham Member QRZ Page

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