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HF NVIS 101

  • 02 Oct 2017 9:53 PM
    Reply # 5292015 on 4968034
    Chris Doering (Administrator)

    Nick,

    I just gone done grounding the rood rack on my Wrangler as well as everything else on the vehicle.

  • 03 Oct 2017 8:52 AM
    Reply # 5292819 on 5292015
    Chris Doering wrote:

    Nick,

    I just gone done grounding the rood rack on my Wrangler as well as everything else on the vehicle.


    Nice. I'm curious to see it on Saturday.
  • 10 Oct 2017 1:40 PM
    Reply # 5307470 on 4968034
    Deleted user

    I have done more research on NVIS in the last 6 months than I would care to admit. Here is a really well done article (pdf).

    http://www.oe3xec.at/wp/wp-content/uploads/2015/02/Philippines_NEAR-VERTICAL-INCIDENCE-SKY-WAVE-NVIS-PROPAGATION_1-0.pdf

  • 11 Oct 2017 5:00 PM
    Reply # 5309594 on 4968034

    Good read, Rick. This is another good one that I found: http://kv5r.com/ham-radio/nvis-antennas/nvis-page-2/

  • 12 Oct 2017 8:10 AM
    Reply # 5310591 on 4968034
    Chris Doering (Administrator)

    Both are good reads. Thank you for sharing. I'm curious of a test we might perform using a vertical antenna (DX) behind a mountain. We seek out the condition where DX no longer works and then try the NVIS.

    Perhaps we can try something of this from two remote locations in Nov. on the HF recon.

  • 12 Oct 2017 10:40 AM
    Reply # 5310882 on 4968034

    Yes, testing NVIS in the field would be great. I am about to buy an Alpha antenna. I've seen it on youtube perform well with and without the NVIS element.

    It would have to be stationary mobile though in order to have a horizontal element. I don't think a vertical antenna alone can do NVIS well. It would also be interesting to experiment with a dipole.

  • 13 Oct 2017 7:52 AM
    Reply # 5312476 on 4968034
    Deleted user

    I am making a list of things to test on the HF Recon.

    The vertical dipole made from hamsticks does work, we have used them in the past and I will be bringing mine to the Op.

    A long stationary dipole works at base camp as demonstrated last weekend.

    The bent over CB antenna needs to be tested again, I have my doubts about it.

    A vertical will still get around things at HF freq more than VHF but never as much as NVIS.

  • 13 Oct 2017 9:04 AM
    Reply # 5312583 on 4968034

    This is one of the antennas on the picture with the Hummer, supposed to be for NVIS.

    http://www.hilomast.com/antenna-systems/nvis-models/mobile-nvis-loop-antenna/

    I like it because it doesn't need a lot of real estate and it's mobile. On the downside, I can't see where I could mount it on my Jeep. I don't have a rack and at least so far I have no plans for one.

  • 13 Oct 2017 2:53 PM
    Reply # 5313050 on 5312583
    Deleted user
    Nick Bretz wrote:

    This is one of the antennas on the picture with the Hummer, supposed to be for NVIS.

    http://www.hilomast.com/antenna-systems/nvis-models/mobile-nvis-loop-antenna/

    I like it because it doesn't need a lot of real estate and it's mobile. On the downside, I can't see where I could mount it on my Jeep. I don't have a rack and at least so far I have no plans for one.


    It is a magnetic loop. I have one at home that i made for 40 meters out of copper pipe. It is about 5 feet in diameter. It worked ok, but was really finicky to tune.
  • 15 Oct 2017 8:18 AM
    Reply # 5315546 on 5313050
    Rick Bean wrote:
    It is a magnetic loop. I have one at home that i made for 40 meters out of copper pipe. It is about 5 feet in diameter. It worked ok, but was really finicky to tune.
    Finicky is a friendly word for the Hilomast Antenna, it's VSWR is listed as "Less than 2:1" when tuned.  For an antenna that has a built in tuner, that's less than optimal.
    For the HF session planned for November, I think I will try my G5RV in Twentynine Palms, with a backup plan being an ATAS-120, but the later is not a good NVIS antenna.
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