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Ideal antenna for living in a hole

Discussion in 'General Ham Radio Discussion' started by archjeb, Jun 27, 2018.

  1. archjeb

    archjeb Member

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    Folks,

    Hope all is well.

    Just getting started in HF after a long hiatus.

    Back in my old place, I used a simple vertical (A99) for 10 meters back when conditions were good (~30 years ago). But I lived in a flat area with a clear view of the horizon. I did pretty good with causal DX.

    Now, I live down in a hole of a valley between two hills with no real view to the horizon. Hills and trees block my horizon. I have about a 30 degree view from vertical of the horizon.
    That being said, I built a fan dipole for 40/20/17/12/10 and its tuned for each of the general segments around 1.2-1.8 swr using my antenna analyzer.

    When I tested it near the ground, I could make some distance contacts. But when I raised it up on the roof, I'm deaf!
    So I'm thinking its because the takeoff angle has lowered as I've raised it above ground to around 25' and that is what is affecting my TX/RX. It looks like the higher take off angle being close to the ground performed better.


    I'd like to place whatever antenna I use on the mast that is on the roof. I have young kids and having the antenna near the ground is not what I'd call ideal.

    Given these constraints, any recommendations for antenna designs for HF based on the above bands?

    Given I'm at 350' elevation and the hills on both sides of me are at 800'...I don't think I have a whole lot of options.

    Any pointers would be appreciated.

    Thanks,



    -J
     

  2. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    At 25 feet on HF the take off angle is still pretty much straight up on the low bands and still very high on the higher bands. The take off angle will not have lowered that much. There MUST be a different reason either propagation or SWR changes.
     
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  3. archjeb

    archjeb Member

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    Perhaps propagation changes. SWR didn't change much after I mounted it under the eave (under eave to protect it from the weather). The only physical change was a slightly steeper inverted v shape to match the roof slope - around 5 degree more slope.

    The SWR moved up around .2-.3 reflected; basically the antenna looks electrically longer now for each band, so I need to get up on the ladder and trim a little from each side --- or I just leave it alone at the 1.5-1.8 SWR.

    At any rate, in the end, I'm wondering if I should move to a different antenna design given my geography restraints.

    Any suggestions? Or should I stick with the fan dipole?

    I'm in the Pacific Northwest, so something rain/snow durable would be key. Wind is not much of an issue because of the hills and trees. I think my wind speed has topped out at 30mph in a 65mph wind storm.

    -J
     
  4. archjeb

    archjeb Member

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    I should also note,the fan dipole is positioned North to South given my house orientation. My 'window' to the sky/horizon (other than straight up) is to the North and to the West. East is blocked by the hill that towers 500' above me. South also is elevated several hundred feet. I'm not exaggerating when I say I'm in a hole :)
     
  5. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    You need to get that antenna out in the open...mounted 2 or 3 ft away from the house under the eve...is differently going to affect performance. Do you have any trees or other structure to mount the antenna on? To get it more height and more in the open?
    I live in a river valley...average terrain with-in 2 miles my of location 2-300 ft higher in most directions...My wire 75/40/20m antenna at 45 ft...I work coast to coast and DX on regular basis...My 6m beam at 45ft, worked coast to coast, have even worked Africa /Iceland/Greece so far this yr...it can be done
    All the Best
    Gary
     
  6. archjeb

    archjeb Member

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    Hi Gary,

    Thanks for the feedback.

    Most of the trees within 50' to 100' of the house I've cut down because of being sick trees. I'll have to think through what options I have away from the house. At this point, it would be a coax run 100' from the house just to get to some trees before I even get vertically up the tree. Vegetation on the hillside to replace dead/sick trees is grape vines - so pretty low profile/height items.


    -Jeremy
     
  7. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Gary has the likely reason. An antenna mounted under the eve is not going to perform NEARLY as well as one in the open. When I was getting started in radio about 100 years ago :ROFLMAO: I had a dipole mounted on the side of the house. The house was located on top of a hill with really great views. My signal still sucked. I moved it out from the house and got it up about 15 feet and it made a huge difference. Then came the beam and a tower on that hill and the rest is DX history. :D
     
  8. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    Jeremy: Here 's a thought or two. The mounting location on or near the Eve could be used for a support. Think about this, mount an Eye bolt with pulley attached...Then string a good Dacron type rope possibly 3/16th's to 3/8th's size thru that pulley. Then use a fishing pole or sling shot to shoot other end of the line in those far trees, as high as practical. Then affix your fan dipole hanging from that support line...center of dipole on support line far enough away so the end of dipole past roof line of house...stretch dipole and hang off support line...allow coax to hang straight down from center feedpoint to ground as far as practical and bring to shack location.Try not to parallel coax with antenna back to house. This would get antenna out in open but not have it hanging where children would be a concern....Think about this, the antenna may slope from high far tree and does not have to be pulled taught. Center insulator should be affixed so not to slide on rope. Hang with short piece of rope off support rope and tape so it will not slide or move on main support. Then do same with ends allow a little droop this allows for movement and again does not have to be pulled Taught...Think about this an see if you could make this work.
    Jeremy by chance do you have an external HF antenna tuner? This will open up other ideas! :)
    Give the support rope idea some thought and see if you could do something like this.
    All the Best
    Gary/W9FNB

    https://www.qsradio.com/shop-now.html#!/Antenna-Rope-&-Hardware/c/8424495/offset=0&sort=normal

    https://www.dxengineering.com/searc...toview=SKU&sortby=Default&sortorder=Ascending

    http://www.randl.com/shop/catalog/p...ts_id=70901&osCsid=iavmv88qcifbnlsh8i7fmiurd6
     
    #8 BJ radionut, Jun 28, 2018
    Last edited: Jun 29, 2018
    Grinder74 and Shadetree Mechanic like this.
  9. archjeb

    archjeb Member

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    Guys,

    Sorry for the delayed response. Thanks for the suggestions.

    I'll try moving it first out from under the eve to my mast that has my 2m/70cm antennas. At least that will put it out into the open for starters.

    Gary, I have no tuner; that's why I built the fan dipole to mitigate that.

    My biggest concern about tree's around here, is we get freezing rain from time to time and any ice weight on the dipole, along with the tree sagging looks like a recipe for antenna repairs. I guess any choice is a compromise...

    -Jeremy
     
  10. binrat

    binrat WDX Club Coordinator
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    Jeremy.
    Suspend the dipole off of pulleys fixed in the tree. Other end of the rope is a bucket full of rocks / dirt. I did that on a 80/40/20/10 dipole. Worked great.
     
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  11. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    Jeremy: I understand your concern for trying to keep your "antenna safe". You have put much work into it to make it. I compliment you on your effort.
    The truth of the matter in many cases is this, the antenna work is never done, most certainly when it comes to HF antennas.
    I live in the Mid-West(central Indiana). The weather here can be all over the board in a year's time. We have Ice Storms, Blizzards, Tornadoes, Extreme Thunder storms with high winds, hail and blinding rain driven by 50-70+ mph winds. We can even have the effects of Hurricanes even this far inland.
    These kinds of conditions exist year-round in the Mid-West and many parts of the U.S.
    We can have most or all of these conditions year round. I have seen snow in June, tornadoes and killing thunder storms in December. I lost my entire antenna farm to Hurricane IKE (late 90's or early 2K) when it came inland and parked over Indiana, with sustained winds of 60+ mph for over 6+ hours. I lost a 54 ft. free standing tower, Mosley beams, stacked VHF antennas and many others in that storm. I was one of just many in this area. I knew op's that lost multiple tower set-ups and equipment as well, due to winds and lighting strikes.
    I am just trying to point out, I understand your concern.
    The overall truth is, you build and you fix when necessary, and you learn and correct your mistakes in construction best you can. Then you go back to enjoying your efforts.
    You do your best and go forward. I have learned that skimping here or there on rope, pulley's, wire type and soldering, will only bite you in the backside sooner.
    The best efforts and all the right equipment, are still no match for Mother Nature's Rath.
    You learn from your efforts and you build again.
    There are many here to help, with their experience and knowledge. I hope I am one. I have operated from apartment buildings, to homes with Postage Stamp size lots, to portable locations where electricity is not even available. I and many others have done the same, you learn what works and what does not.
    I think that is one of the more interesting parts of this hobby, I have enjoyed for going on 40 years now as a Amateur radio operator.
    Good Luck and hope to work you soon.
    All the Best
    Gary
     
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  12. archjeb

    archjeb Member

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    Thanks for info and encouragement. I guess I have more work to do :).

    -Jeremy
     
  13. archjeb

    archjeb Member

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    Gary,

    On your question about an external tuner; I could buy one if needed. Are you thinking an end-feed antenna from house to a remote tree?

    -J
     
  14. archjeb

    archjeb Member

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    Hello all,

    I'm revisiting this now that I've tested my fan dipole side by side with a vertical antenna (specifically the Comet CHA-250B). I moved my fan dipole to the top of a mast above the house so that its 25' above the ground.

    Its about the same height as my CH-250B that I'm testing with an antenna switch. What's really weird is that the noise floor is higher with the fan dipole compared to the vertical - which I was really surprised about. Not sure why that's the case.

    Also, the vertical seems to be performing better - receive wise. Given the Comet has a matching transformer and is not really efficient on the lower frequencies; I was really surprised to see the difference in favor of the vertical. I haven't tested TX, this is just RX that I'm using as a point of reference for signal strength.

    Maybe its my antenna build quality that sucks :) and that is why my home made fan dipole is not receiving as well :unsure:

    Any any rate, I could see about buying an antenna tuner if you think some other alternative antenna types would be better to try.

    Thanks,

    -Jeremy
     
  15. fogdog

    fogdog Active Member

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    I live in a similar location; 3,000 ft elevation, but thete are ridges on all sides up to 6,000 ft. The 1 /2 wave Dipole I built didn't hear very well. I had it up in some trees about 15 ft up. I tried horizontal and inverted V.
    I decided to try the Imax 2000, and have been making contacts ever since. Big differance for my particular situation. The Imax is a bit noisy, and so is my radio but I get good signal and audio reports daily. It works for me. I should note that I only use this antenna on 10 meters.
     

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