CrankIR 40m-2m Vertical

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by WM7C, Jan 28, 2013.

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  1. WM7C

    WM7C XML Subscriber QRZ Page

  2. KO6WB

    KO6WB Premium Subscriber QRZ Page

    It looks like a skeleton slot antenna variation. A bit smaller and perhaps actually a half slot antenna or half of an SDR. You could always make one and see what your's does. Unlike other antennas SteppIR has there is no motor on this one for auto tuning and no sense circuit either. It's performance won't exceed that of a simple dipole at least not on the HF bands and it could take on the dimensions of a full wave loop on the VHF bands. Perhaps a harmonic antenna as the frequency goes higher. An antenna that is one wave on 4 meters will still make an okay antenna on 2 meters in theory at least.
    Could be a low cost unit from SteppIR and that would be a refreshing change.
    Have fun
    Last edited: Jan 28, 2013
  3. K4SAV

    K4SAV Ham Member QRZ Page

    This question was asked on eham. Here was my reply.

    There doesn't seem to be any info on the website, but it's pretty easy to guess how this works and estimate the performance. Here is my guess:

    If you blow up the picture, you can see two different kinds of wire/cord. That will be the junction of the conductive wire and a cord of some kind. This cord rewinds back onto the reel, so turning the crank you can extend out the amount of wire you need to make it resonate at the right frequency. You will need radials of some kind because this is just a vertical. With an 18 ft mast, it will be a normal vertical for 20 thru 2 meters. The SWR should be the same as you would expect from a standard vertical. At lower frequencies the wire loops across the top and back to towards the ground. That will produce a lower feedpoint impedance and higher SWR on the lower bands. The lower feedpoint impedance will also produce more ground loss. The amount of that loss will depend on how many radials you have. There should be insignificant gain loss just from looping the wire back towards the ground. The only significant extra loss will come from the feedpoint impedance being lower and causes the ground impedance to be a larger percentage of the total impedance, and so more ground loss.

    So who will be the first to build one of these and put a motor in place of the crank? The difficult part will be keeping the amount of wire going out of the reel equal to the amount of cord going into the reel. (Hint: In a blown up picture, notice there appears to be a springy horizontal support on top of the mast.)

    Jerry, K4SAV
  4. NA0AA

    NA0AA Ham Member QRZ Page

    Well, they have come up with innovative stuff before.

    Will be interested to read test reports when they come out.
  5. N0AZZ

    N0AZZ Premium Subscriber QRZ Page

    As many have found with antennas less moving parts = less problems. A fiberglass telescopic pole and a fishing reel about the same well under $75
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