what antenna would you build?Given

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KA4DSK, Apr 8, 2012.

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  1. KA4DSK

    KA4DSK Ham Member

    Given option which antenna would be best for 40/20/17/15/and10
    an ocfd or a fan dipole i have the materials and space to make
    both but can only place about 30 feet above ground.
    feed line from radio to antenna would be about 60 feet.
    THANKS TO ALL THAT RESPOND.Frank ka4dsk
     
  2. AD4J

    AD4J Ham Member

    Of the two options you mention, I'd go for the fan dipole because it is less likely to have common mode current problems leading to RFI and noise pickup issues. However, it will take some fiddling to get the lengths right for resonance on all those bands, because the conductors interact, particularly on the higher bands.

    My preference is for a third option - a 40 meter dipole feed with balanced line, using a balun and tuner. That has been my main antenna for several years now and I've been very successful with it. Combined with raised quarter wave radials for 80 & 160 meters, I also use it as a top loaded vertical on those bands. This antenna has produced contacts on all 11 bands from 160 through 6 meters for me. The downside is that there are some deep nulls in the azimuth patterns on the bands above 20 meters, but even a half wave dipole has significant nulls off the ends.

    Jim
     
  3. KG4NEL

    KG4NEL Ham Member

    That would be my choice as well.

    Or, if you have the supports for a horizontal loop, you could build it as a full-size loop for the lowest band you're interested in. Feed it the same way as you would a doublet, to a good antenna tuner.

    http://srgproperties.inetusanow.net/files_custom/9467_2192.pdf
     
  4. KB5UBI

    KB5UBI Ham Member

    How much space do you have? I also vote for center feed with the balanced line. Put as much wire up as you can, 66' or more if you can and feed it with ladder line all the way to the shack through a 1:1 current balun at the tuner. You can trim the feeder if necessary.
     
  5. KB4QAA

    KB4QAA XML Subscriber

    Neither.

    I would put up a Center fed dipole fed with balanced line.

    A fan dipole is too fussy for me to fiddle with. OCF? Pulleease.
     
  6. N0SYA

    N0SYA Ham Member

    Fill the available length with a single wire dipole, feed it with coax, add some ferrites to both ends of the coax, and force feed all bands via a transmatch.
     
  7. KC8QVO

    KC8QVO Ham Member

    Isn't a balanced antenna (equal lengths on either side of the feedline) fed with balanced line to a tuner called a Doublet?

    I thought a dipole only referred to a resonant 1/2 wave length antenna built for one band (or, a portion of one band).
     
  8. N5YPJ

    N5YPJ QRZ Moderator

    Center fed doublet 66 ft long fed with ladder line. I like fan dipoles but my experience has been that when one adds unrelated harmonic bands to the antenna "the fun begins" in question to getting all of the elements properly adjusted where we are "one big happy family". As long as it is 40-20-10 the adjustment is a lot easier.
     
  9. KA4DSK

    KA4DSK Ham Member

    Hi Jim will give your option a try,i have about 75 feet of clear space between trees that i will be
    able to use for end supports .wiil have to get some ladder line and balum<not sure 1/4 or 1/1 coax coil type>
    will need to use coax in to house as i need to enter at ground level and come up from basement to first floor
    house is stone and i don,t to chop holes in the thick walls. the worst thing i could find next is my trees are not located for best sig to the week station you need HI HI frank
     
  10. KB4QAA

    KB4QAA XML Subscriber

    1. Yes, sometimes. Tuning arrangements have no bearing on antenna naming conventions or definitions.

    2. No.
     
  11. N2EY

    N2EY Ham Member

    ZS6BKW

    Google is your friend.

    73 de jim, N2EY
     
  12. WA4FNG

    WA4FNG Ham Member

    I would also vote for the balanced-line fed 40m doublet. If you choose this option, you may want to research alternate lengths other than 66'. When feeding with ladder line the actual length can be a little shorter, or longer (non-resonant) and still work efficiently. By purposely making the antenna non-resonant on all bands, tuning is sometimes easier.

    Feedline length plays a part in this as well. There are some lengths to avoid. Here is more info on this:
    http://www.hamuniverse.com/feedlinelengths.html
     
  13. KF6A

    KF6A Ham Member

    I would go with a non-resonant doublet fed with ladder line. Something like an 88' doublet, or longer if you have the room. Remember, the legs do not have to be straight and the ends can be bent, left dangling, etc.
     
  14. N0AZZ

    N0AZZ Ham Member

    OCFD a no brainer easy to make and setup they work great for what they they are all wire antenna are lacking. Go to the buckmaster antenna sight and use there design I have bought 4 of there antennas in the last 6 years for different applications. The one up at my house now a 270' @ 55' 3KW model covers 6-160m I use it mostly for 160m. I have very good non wire antennas that cover all bands 1.2 gig-40m yagis and beams for 10-80m I have a excellent vertical optimized for 80m.

    The OCFD @ 32' design let me work 139 countries with 100w in 11 months using LoTW only plus it's coax fed no twin lead problems.
     
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