End fed HF antennas?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by 2E0ILY, Apr 9, 2012.

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  1. 2E0ILY

    2E0ILY Guest

    I am wanting to replace my random piece of long wire antenna for something more efficient that I can safely expect to load up for transmission from my old boat anchor Yaesu FT-902DM. The restriction is that it has to be end fed as it goes across our front lawn and I don't want to to be either visually intrusive, nor needing a cable other than the feed in cable running across the place. I have done a very crude sketch of my two obvious anchorage options. My "shack" is the upstairs of our bungalow, and the antenna feed in needs to be via the porthole window it has, at the end of the house. The current long wire has its anchorage above this window, on a rope with two insulators, that exits the brickwork above the window at a height of about 23 feet. The other end of my random wire has another rope anchorage with two insulators at the top of a tree in the garden, at a height of about 30 feet. The length of the wire itself. less guy ropes, is about 190 feet. There's another handy tree in the garden about 100 feet from the house end anchorage, shown on the drawing. I can use that as a second anchorage, or instead of using the tree about 200 feet away. Can anyone think of any half decent options using these 3 fixed points for an HF aerial for 160, 80, 40 and maybe 20 metre bands? The drawing can be accessed at http://www.gatesgarth.com/plan.jpg I can run a ground from the garden beneath the level of my shack. The ground wire will terminate in a six foot galvanised earth spike driven into damp soil, it will by necessity be at a distance of about 25 feet from the transceiver and ATU. I know it's not ideal but I have to work within these criteria. Thanks.
     

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  2. W5DXP

    W5DXP Ham Member QRZ Page

    The Zepp airships had the same requirement - how about a Zepp antenna?
     
  3. KO6WB

    KO6WB Premium Subscriber QRZ Page

    Your ground is going to be highly reactive and can cause all kinds of problems. One way to deal with that is to use an artificial ground. This will tune your ground for better operation. You can get one from MFJ the model MFJ-931. Some have used a spare antenna tuner for this purpose. This alone should make for better operations with any end fed antenna. The only end fed antennas that I can think of that will work where you want to place them is the end fed zepp and a random wire. One thought with your setup would be to put a wire to the tree 100 feet away and one wire to the tree 190 feet away and a joining wire between the two trees. This would make a loop. You would have to use a short section of ladder line at the point where the two wires from the trees meet at the bungalow. Use your ATU to tune the bands. If it has a balun in it you would have to connect the ladder line to it. If you don't have a balun then get a 1:1 current balun and connect that to the SO-239 terminal and the ladder line to the balanced side of the balun. This will work very well.
    One antenna book that will help is the Antenna Toolkit. You can get it at; http://ok1ike.c-a-v.com/soubory/ant_txt/antenna_toolkit_2e.pdf. It has various ideas in it and covers theory and practical applications.
    Hope this helps
    73
    Gary
     
  4. 2E0ILY

    2E0ILY Guest

    Thanks for the fast replies and the link to the Antenna Toolkit book, which at firts glance looks very readable at my level of knowledge. I can already see that end fed is going to be very compromising. the only other possible solution is if a centre, or offset centre feed could be run to the house wall underground, shallow buried under the lawn, done by slitting and lifting the turf with a sharp wide spade. It would have to be done when `er indoors was away for the day or weekend ;) Would that be feasible? I would have to then run the feeder round the corner of the house and up behind a plastic drainpipe to conceal it. Ladder type feeders would be out, single runs of co-ax possible. Even I do not want the place looking like GCHQ, if you see what I mean? :) Thanks.
     
  5. W9GB

    W9GB Ham Member QRZ Page

  6. KJ4CMG

    KJ4CMG Ham Member QRZ Page

    Run a wire to both trees and have a dipole antenna? The loop idea sounds good too, though not exactly circular.
     
  7. WA8FOZ

    WA8FOZ Premium Subscriber QRZ Page

    This QTH begs for a triangular loop, strung between the apex of the house and the two trees. this loop could be used successfully on all the bands you mention, and probably the other HF bands as well. This is a balanced antenna, and the ground is irrelevant.

    This antennacould be fed either with ladder line going from your antenna tuner to the loop, or by as short a length as possible of the best coax you can get to a CURRENT balun at the apex/feedpoint.

    Catch you on 20 meters!
     
  8. 2E0ILY

    2E0ILY Guest


    That sounds promising! I will check them out in the book, but if you can be yet more specific that would be great. Thanks Bill. Is a current balun something I could make, or is it best to buy one commercially? Has it to be tuned to the antenna wire lengths? Does a multi band triangular loop depend on traps? If a ladder feeder could be run from the apex of the "triangle of wire" by the porthole window, and in to my upstairs shack via that point, that would be fine, but how would I bring ladder feed through a wooden window from that has about a maximum of half an inch between brickwork and the glazing unit it supports? I have no knowledge of ladder feeder, as in its physical size, or requirements when fed through things like window frames. Cheers.
     
  9. KO6WB

    KO6WB Premium Subscriber QRZ Page

    As I mentioned the loop would be a very good antenna for your use. The feed point would be at the point that's close to the bungalow. It can be simply two wires that are held apart by plastic or wooden sticks. The seperation would be anywhere from 2 inches to 6 inches. You could drill two small holes in the wood frame of the window and bring the feed into your shack and to the tuner.
    You can make a current balun but they are not expensive to buy. A 1:1 current balun would do very well.
    The Antenna Toolkit has some information on baluns and loop antennas.
    Take a look at page 121 of the Antenna Toolkit book. This is what you would do except your loop would be a triangle.
    See if this will work for you.
    73
    Gary
     
    Last edited: Apr 9, 2012
  10. WA4OTD

    WA4OTD XML Subscriber QRZ Page

    I would do either a "Vee" dipole antenna...maybe fed with twin lead. Or else put in a vertical.
     
  11. 2E0ILY

    2E0ILY Guest

    I think I will try a roughly triangular loop for a start. It gives low visual impact, puts a lot of wire in the air, uses existing anchor points (trees), and brings the feedpoint and hardware back to the house window area. I have been given a late nineties ARRL handbook (great product, a real reference source...), and it mentions current baluns made from sliding a fixed number of ferrite rings over certain types of coax. What are the thoughts on building such a current balun for my purposes? As this is experimental it allows a balun to be quickly made that appears to need no enclosure, so if it doesn't work not much time or cost is wasted. Thanks for all the help!
     
  12. KB4QAA

    KB4QAA XML Subscriber QRZ Page

    A better type is a Current type BalUn. Probably a 1:1, but some people use a 4:1.

    Tom W8JI has discussion about this on his site.
     
  13. W5DXP

    W5DXP Ham Member QRZ Page

    Here's one fed close to the ground with a 50 ohm feedpoint impedance.

    http://www.w5dxp.com/40mtri.htm
     
  14. WA8FOZ

    WA8FOZ Premium Subscriber QRZ Page

    Most of your Q's have already been answered, but in the interest of redundancy:

    Is a current balun something I could make, or is it best to buy one commercially?


    Either. Not too dear to buy.

    Has it to be tuned to the antenna wire lengths?

    No

    Does a multi band triangular loop depend on traps?


    No

    If a ladder feeder could be run from the apex of the "triangle of wire" by the porthole window, and in to my upstairs shack via that point, that would be fine, but how would I bring ladder feed through a wooden window from that has about a maximum of half an inch between brickwork and the glazing unit it supports?

    The ideal would be feed-through insulators, as in this commercial product from MFJ: http://www.mfjenterprises.com/Product.php?productid=MFJ-4600
    You could make up something like this with just feed-through insulators and close the window in it. Or replace a window pane with wood or plexiglass. Here's a nasty secret: I have at times just drilled two holes through the wood, plexiglass, or the sash and run wires through. Crummy design but it gets by for lower power, if no metal is within a few inches.

    If none of these options please you, then use the coax-to-current-balun mounted outside. In all, this should take less work to do than to talk about!

    I have no knowledge of ladder feeder, as in its physical size, or requirements when fed through things like window frames. Cheers.
    Most of us use 450-ohm vinyl coated twin lead: two #16 or so conductors about 1.25 inches apart; or 300 ohm line, about a half inch wide. Makes no difference which you choose in your installation - 300 ohm TV twin lead would be OK.

    Have fun!
     
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