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Re: [sierra_wilderness_radio] Re: Portable Antennas

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  • w9ya
    A couple of salient points about 1/2 wave antennas, baluns, and end-feds. There is no such thng as an end-fed with a counterpoise. i.e. Either an antenna is
    Message 1 of 3 , Feb 24, 2009
      A couple of salient points about 1/2 wave antennas, baluns, and end-feds.

      There is no such thng as an "end-fed" with a counterpoise. i.e. Either an antenna is fed from one end or it is not, as the "counterpoise", when connected to a/the network (your antenna,rig, and tuner combination), **IS** a part of the antenna.

      And yes, sometimes center fed antennas may require a balun if a particular performance (pattern) is desired when used with coax. Why ? .... because coax is a three terminal transmission line, and the outside of a coaxs can radiate depending on various factors. (The specific length of coax being a common reason for such radiation and the use of baluns to mitigate this effect being a "solution".) This coax radiation will most likely be a departure from the classic resonant dipole pattern. (BTW this change may be an enhancement or a detraction depending on your desires for such an antenna. But it is real and a contributing factor in the resulting radiation pattern. And baluns are a great way to control coax radiation.)


      On Sun, Feb 22, 2009 at 6:09 AM, Donald McBride <McBride_D@...> wrote:

      Hello Frank,
      RE: Antennas
      Nothing is easier, as you know, than a simple half-wave dipole
      fed with coax, and I have several depending upon what portable
      rig I'm carrying to the field. However, my 25-year old 3-band
      "jumper dipole" is my favorite.  With sections separated by
      insulators and small alligator clips, it can be quickly set for 20,
      30 or 40 meters by just temporarily lowering the center support
      Perhaps like you, I've experimented with balanced line-fed
      doublets and they certainly work, but coax is just so much
      easier to pack and deal with and doesn't require a balun. 
      Another antenna you may also have tried is the "Dollar Special"
      found on the Internet at: 
      While inflation has run that up to $2 these days, two packs of
      Dollar Store speaker wire can be turned into a three-band
      end-fed with tuned counterpoise and still wrapped up for
      transit in a plastic sandwich bag.  I carry mine all the time in
      case something goes awry with my dipole, such as a broken
      wire or forgotten whatchamacallit or whatever and have
      worked the Ukraine with it from the park with my 2 watt SIERRA.
      Oh, and did I mention that all these antennas are "cheap"? <grin>
      ... 72/73,
      ... Don

      Re: Battery

      Posted by: "Frank MacDonell" kd8fip@...   fmacdonell

      Sat Feb 21, 2009 7:33 am (PST)

      Thanks Don - What kind of wire do you use? Do you cut to half wave?
      What do you use for feeder wire? Thanks Again!

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