80M antenna within a confined space

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by STDYIN, Aug 2, 2020.

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  1. STDYIN

    STDYIN QRZ Member

    I have 100 ft to work with, North to South along the back side of the yard
    so that means im 30-40 feet short

    It also has to be an Endfed antenna, as the home owner would skin me alive
    if she sees a cable hanging down in the middle of her yard,
    Thought of a windom, hiding the cable behind the antenna and through the trees/fence,
    but would add 40-60 feet of cable to get to my window,
    ending up as 100ft
    so--nope still within her yard if run directly :(

    I was looking at buying one of these
    ,
    https://myantennas.com/wp/product/efhw-8010/
    ,
    but I dont have the length to hang it, without cutting trees, and that is a BIG no-NO
    I thought about letting the one end hang, ? down the 30Ft ?
    even if I slope it with the highest end at the "N" position 60ft up
    im still too short of space
    the "S" postion will be at 20-30 ft up to try and keep it out of her sight,


    Then i was surfing on google and ran across this topic, Here :)

    https://forums.qrz.com/index.php?threads/half-size-g5rv-vs-3-dipoles.560875/

    Post #8
    and I saved the PDF file,

    so im wanting to build the 9:1 UnUn great directions by the way,
    and somehow in some configuration without radials
    pull in 80M

    so Far
    I AM NOT
    Transmitting, Just receiving right now
    BUT am studying and having alot of FUN listening to all the folks that can transmit
    and I want a REAL antenna, as my ground line wrapping around the house is almost in
    or will be by winter

    Oh and I do have a MFJ 949D Tuner

    cheers
    john
     
  2. N4UM

    N4UM Ham Member QRZ Page

    You can use a simple quarter wave 80 meter "Marconi" approximately 65 feet long installed as an "Inverted L" and fed directly at ground level with coax. Install as many radials in the grass as convenient or use one or more counterpoise wires. Run as much of the antenna wire vertically as convenient and the remainder as horizontal as possible.
     
    W0PV, AK5B, WA9UAA and 1 other person like this.
  3. STDYIN

    STDYIN QRZ Member

    I have many feet of the green coated wire fencing in all sorts of widths, 4ft tall, from my fencing for chickens
    can that be used for the radials/counterpoise ? soldering wires to them? and spreading them out
    do they have to be buried? of can they just be run along the ground through the bushes.leaves ?

    Im hiring a "tree-Climber" friend to go up into two trees and hang my pullys/rope,
    but im to old and beat up (heart attacks) to dig trenches,
     
  4. SM0AOM

    SM0AOM Ham Member QRZ Page

    As long as you are only receiving, the actual antenna size is quite inconsequential. Lengths much below about 1/8 wavelength are however not recommended, as they become increasingly difficult to match.

    What has a large influence is the placement of the feedpoint with respect to the other wiring of the house. When a short antenna is end-fed, its feedpoint becomes in close vicinity of noise carrying conductors, and when the antenna is so short that its feedpoint impedance magnitude lies in the hundreds or thousands of ohms, the coupling becomes worse.

    This deteriorates the received signal/noise considerably,
    and is very difficult to remedy.

    I would recommend, if possible, a balanced mid-point fed antenna together with an antenna tuner. Its actual length is quite unimportant, but should preferably be more than 1/4 wavelength at the lowest frequency of operation.

    Measurements I did during the early 90s on coast station receive antennas showed that a building-mounted short end-fed antenna showed an S/N penalty of at least 10-15 dB compared to resonant dipoles in the low HF range.

    73/
    Karl-Arne
    SM0AOM
     
    PY2RAF likes this.
  5. N4UM

    N4UM Ham Member QRZ Page

    The radial wires don't have to be buried. They can be laid on the ground and fastened down every few feet with lawn staples (u-shaped bent pieces of wire that can be purchased or home made). Grass will grow over the radials in a relatively short period of time. The radials can be of varying lengths. They should run out in straight lines from the feed point. Try to keep the feed point as far from your house as possible to minimize noise pickup from the house. Sixteen radials as close to 30 feet as possible would be a good place to start. You can always add more later. Check out the ARRL Handbook, or better still, the ARRL Antenna Book, for guidance.
     
  6. W1GHD

    W1GHD XML Subscriber QRZ Page

    The Myantenna model you mentioned will work just fine as an inverted L, and is darn near invisible. Slit the sod and run direct bury coax back to the shack.

    When you obtain General privileges, you’ll have a multiband antenna waiting for you.
     
    AK5B likes this.
  7. KU3X

    KU3X Ham Member QRZ Page

    Try this one. It works as I already made one and tried it. It's less than 100 feet and it's an end fed as you requested.

    http://pa-11019.blogspot.com/2012/04/149-transformer-for-endfed-antennas-35.html

    Barry, KU3X
     
  8. WA7ARK

    WA7ARK Ham Member QRZ Page

    An EFHW antenna that works from 80m to 10m is about 67ft long. The best way to deploy it is horizontal, and as high as possible (best >30ft agl). You can hide the transformer/coax in tree foliage at one end, and run the wire toward another tree to minimize its visibility.

    I created a hamfest presentation slide show that discusses how the EFHW-8010 antenna works. There is a link to the slides at the bottom of my QRZ page.
     
    Last edited: Aug 2, 2020
  9. W1GHD

    W1GHD XML Subscriber QRZ Page

    The 40 meter version is 67 feet, it’s about 130 feet for 80 meters. That’s why I suggested the Inverted L installation.
     
    AK5B likes this.
  10. WA7ARK

    WA7ARK Ham Member QRZ Page

    ...it has been too long since I did those tests outlined in the presentation, I am forgetting stuff I should remember...:oops:
     

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