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Antenna pattern measurements using drones

Discussion in 'Homebrew and Kit Projects' started by W6KCS, Sep 3, 2018.

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  1. W6KCS

    W6KCS Ham Member QRZ Page

    I'm working on a way to use a drone (like a DJI Phantom or Mavic) to fly around antennas and measure their patterns, and wondered if anyone else here has done that (or wanted to) and wants to share notes or ideas. If anyone's interested I'll post my progress.
    W1TRY likes this.
  2. NE1U

    NE1U Ham Member QRZ Page

    I have been lusting for a drone for quite a while. Yet another reason.

    This is an interesting idea. I am imagining circling around in the far field the antenna of interest ... 3 times? ... collecting radiated power levels and averaging. At least some of these drones can be programmed to follow a path, I think.

    The challenges. 1) Making a correlation of the rcvd signal level of antenna (aka probe) on the drone. This should be doable with a little computer modeling assisted validation.
    2) making full loops might not be necessary. Just checking areas of interest might be more interesting for type ham use and quicker.
    3) relating position in 3D space to rcvd signal level. I'll bet there are codes out there already that can do or help with this. Initially, forget the 3D & go 2D on controlled radials. As controlled as controlled can be. For ham use, probably just confirming launch angle (HF antennas) or the location of maximum signal level (yagis & stacks of, or colinears). Just correlating the az/el of maximum field strength versus VSWR might be a thing.

    I might over think things, but for hams simple sophisticated can be useful. Many like to experiment with antennas. Tuning them over various topographies is a leap of faith.
  3. W6KCS

    W6KCS Ham Member QRZ Page

    This is a good reason, so you might as well order one up now :)
    I'm not sure how to measure absolute field strength, which is what you I think are referring to in item 1. I could compare it on each band to a calibrated antenna. The receiver I'm trying out is called an RF Explorer IOT. It covers 15 to 2700 MHz, so it should be good for 15 meters and up. I'm mostly interested in VHF and UHF. I've played with the receiver on the bench and it seems to report level correctly within a dB from -20 to -90 dBm, at least on 2m. Here's the receiver if anyone's interested:

    I have it plugged into the top of an Arduino Due. It's a 3.3v device, so the Due works really well and there are some libraries for it to make it do "stuff."

    Edit: I forgot about the 17 meter band, I guess it'll work there too.
    NE1U likes this.
  4. WA7ARK

    WA7ARK Ham Member QRZ Page

    There was a fellow at the Prescott Hamfest this summer that gave a talk about just this topic. I believe I can find my notes....

    I think he flys a small transmitter on the drone, and logs the signal strength from the antenna under test...
    W1TRY, WB5THT and NE1U like this.
  5. WD0BCT

    WD0BCT Premium Subscriber QRZ Page

    A very interesting suggestion! This would allow far field measurements and I believe it could be used to see how accurate antenna programs really are! It would not surprise me at all if this application of drone technology is currently underway.
  6. K3XR

    K3XR Ham Member QRZ Page

    Interesting thought I would need to get much more practice in with the DJI Phantom before even attempting such a feat . Waiting for the nasty weather we have been having to break so I can go to the fields at the state game lands for some practice. Be interested in hearing of any of your exploits with the drone as it relates to ham radio.
  7. WD0BCT

    WD0BCT Premium Subscriber QRZ Page

    This drone thing is getting interesting. A drone came down in a public crowd of people recently here in Colorado and the local media pointed out that it was illegal to fly a drone over crowds of people w/o permission. I would like to know how this is policed other than after the fact. I guess now I know why most crashed drones have no identification on them!
  8. K3XR

    K3XR Ham Member QRZ Page

    There is recreational and non-recreational flying the recreational requires registration for the size (weight) drones we are discussing here. Also if you intend to fly within a 5 mile radius of an airport you must notify flight control at that airport. Picked a site to practice beyond the 5 mile radius so that would not be a factor.

    If you think you would want to pursue it there is plenty of information by way of doing a search to help you out both with the rules and regs and in selecting the type and price range you might want to consider.
  9. WB0RIO

    WB0RIO Ham Member QRZ Page

    Interesting idea, please keep us informed on how it works.

    A drone could also be used to lift a fishing line feeder over tall trees, the feeder could then be used to
    pull up a rope and a wire antenna.
    K3XR likes this.
  10. K3XR

    K3XR Ham Member QRZ Page

    There are in fact attachments for a drone to drop a fishing line for the purpose of fishing should work very well for dropping a line over a tree.

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