Best HF antenna that does not require a tower?

Discussion in 'General Technical Questions and Answers' started by KB7QPS, Mar 15, 2009.

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  1. AB9LZ

    AB9LZ Ham Member QRZ Page

    Having "flown" several fan dipoles, I'll be the first to warn that they can be a major PIA to install / tune / untangle (after storms) etc.

    Reconsider, the ladder line doublet with a coax whip to a balun (if needed). It's an efficient low maintenance setup.

    73 m/4
     
  2. K3STX

    K3STX Ham Member QRZ Page

    I agree about the PITA about the fan-dipole. Mine was only a simple 2 band job and after a big storm it almost ALWAYS got twisted up. That led to RF in the shack, had to take it down, etc..

    The losses with 10 feet of RG-213 even with a 20:1 SWR are not so big, you can calculate it. It is worth it for the convenience...AND thousands of Hams do it, it works.

    paul
     
  3. XU7XXX

    XU7XXX Ham Member QRZ Page

    Put up a vertical with as many ground radials under it as you can. Don't skimp on the radials by putting down only ten 15' radials...........You will be wasting your time & money.

    On the cheap, dipoles work good IF you get them up at least 1/2 wavelength. The higher the better for working DX, if that is the kind of thing you are into.

    Don't be tricked by company's who want to sell you a $300+ dipole or vertical!!! Go to Home Depot, pick up some wire & start visiting "how to" amateur antenna sites on the Internet. For the whopping sum of less than $35 you will now begin to work the world.



    Tom XU7XXX
     
  4. WM5Q

    WM5Q Ham Member QRZ Page

    Agree, it's a PITA. I tried once. First HF antenna (this is five years ago). Fan-inverted-vee for 40, 20, 15, 10, and 6. Maybe 2 as well, I forget. Point is, it had too many wires and too much interaction, everything was too long. I think it was a total of three times it went up and came down one day trying to prune it. Then I decided to simplify it and took it down to just 40, 20, and 10, with more separation between the wires, and flat-topped. It made it up once before everything tangled up.

    Electrically decent antennas, but a mechanical nightmare.

    Another vote for a single doublet. You said coax feed, but I bet you could make ladderline work. Much simple, last long time.
     
  5. AD5ND

    AD5ND Ham Member QRZ Page

    A dipole cut a little too long for the lowest operating frequency with an automatic antenna tuner at the feed point. Then use coax to the transmitter. The reason for cutting the ant too long is to keep the radiation resistance at a reasonable level on even harmonics. Don't want the caps arcing.
     
  6. K4GTI

    K4GTI Ham Member QRZ Page

  7. K3WRV

    K3WRV Guest

    OK! If you can mount antennas on the roof, my first suggestion would be a small Tribander up there. Mine (TH3 MK3) is mounted on a Rat Shak tv tripod (abt $25) lag bolted to the roof peak. Roof reinforced with 2x6 or 2x8 nailed between the rafters. Totl height is probably around 30 feet. Others will tell you this is not ideal, and it isn't. And it probably won't hold up under an engineering analysis. But mine has been up for 25 years, and has been through several tropical storms (60-70 mph sustained winds with no damage.

    I also use whatever wire I can find - #12 House wire (found a 500 ft spool for $5. Stranded is better than solid, but both work OK. I also like Aluminium Electric Fence wire (about $15 for a quarter of a mile. I interface the feedline and the antenna with brass machine screws with a brass washer separating the feedline and the aluminium to avoid dis-similar metals reactions. My favorite is a long dipole (about 500 ft) fed with ladderline to the tuner (MFJ 941 or KW Matchbox. Others will tell you the antenna will have a lot of lobes and nulls. Mine is run NE-SW, and the only lobe I've noticed is towards Brazil - no nulls. My assumption is that the lobes get all blended together in the ionosphere. Gangbusters on 40 and above (where the lobes should be apparent). Ladder line runs across the basement and is spaced about 6" below the heat ducts, wiring, plumbing, etc. I just ran it through an open window and closed the window on it (no screen installed). It has come down a few times in ice storms and hurricaines, but I just "Western Union splice" it back together. The antenna is almost as good as the tribander, unless you aim the beam very carefully - then the beam beats it.

    The aluminium wire is very light and easy to work with, and works great for Beverages and V-Beams. And cheap enough that you can try lots of different antennas to see what works best for you.

    Hope this is useful. An article in QRP Quarterly, (Summer, 2007?) says to forget the balun. The author measured losses of up to 6.5 DB with some baluns, and found very few / insignificant balance problems just hooking coax directly to the ladderline.

    de Bob
     
    Last edited by a moderator: Mar 16, 2009
  8. KC2UGV

    KC2UGV Ham Member QRZ Page

    If you have an attic, then a di-pole in the attic works. If not attic, you can run the antenna down the length of your abode.

    If you have window access, R&L Electronics has a window antenna (Haven't tried it yet).

    But, I have great luck with the attic dipole.
     
  9. WA9CWX

    WA9CWX Ham Member QRZ Page

    A LOT depends on how ambitious you really are... I have used for decades almost every antenna mentioned in the above excellent posts, except the switched loops. With a big yard, tall trees and a decent radial field an inverted 'L' works wonders on all bands, I had 2 of them, one for asbout six months, and it worked VERY poorly, I did not have a radial field, JUST a good earth ground.
    The second one I used for a few years, with a few long and a few shorter radials, worked great, domestic and DX, all bands. I even worked a VK on 160 meters, no amp, from here in the midwest.

    As for 'fan' dipoles, I have a 40/80 works great, wires are at right angles to eachother, so no tangles in wind, has never given me a problem, and yes, I have a LOT of DX on 40 and 80 and 30 with that antenna.

    LASTLY , I have a long (400') dipole fed with ladder line, works good, my ladder line, for a SHORT disatance just goes into the house with all the other coaxes, through a plastic pipe in the basement, that little 'bump' in impeadance seems to make zero differnce in overall performance.

    ALL my antennas use #12 or #14 solid copperweld. The thinner copper covering on the stranded copperweld weares off sooner and it rusts. However for 3 years or so ANY WIRE will work just fine.


    Frank,
    (PS, you have the IDEAL antenna space for serious Lower frequency antennas, good luck with whatever you choose)

    AN added note on radials, IF you use pliable wire, lay it flat and close with no gaps, it willl dissapear and bury itself in the grass after a few weeks.


    I used bright orange plastic coverd #16 stranded wire, and a lot of bobby pins tro hold it down, in the yard for my phased verticals, there are 60 or more 35' and a few morwe, longer, radials in our yard, I absoloutly can not see them, evem when LOOKING for them.
     
  10. DL1JRK

    DL1JRK Ham Member QRZ Page

    I was just visiting a fellow ham's (DJ7PI) place today (actually to buy a PA). He lives in a rented single bedroom apartment and is also not allowed to set up towers. Instead he placed a 12m aluminium telescoping mast in the center of the garden(tied to an old concrete fence pole with cargo straps) and stretched out a cobweb of resonant dipoles to cheap wooden bean poles (those 10m long stakes used for growing beans or other ranking plants, bamboo would do as well). This guy has been in the business since almost 30 years and has done DX all over the globe with this setup.
    The dipole wires are practically invisible, unless you are really looking for them and the wooden stakes and the olive drap aluminium mast (army surplus) don't attract any attention in the rural surroundings. In the past he used a large fir tree to support a vertical for 80m (until the landlord decided to cut it down). He told me that he climbed up the tree and attached a 10 ft fiber glass rod with a pulley attached to it near the top of the tree. Then he ran a wire up and buried some rabbit wire beneath the surface as a ground. Add a remote controller tuner at the feed point and Bob's your uncle.
    An additional bonus is that the whole setup didn't cost more that maybe $150 (the most expensive item was the aluminium mast) and he can take the whole shebang down within 2 hours should he decide to move out.

    Jan, DL1JRK
     
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