Math Q. cuz I'm bored...

Discussion in 'Math' started by mbohuntr, Jun 25, 2009.

  1. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
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    I'm trying to calculate dipole lengths, and I need the calc for wavelength. isn't it 186000(light speed)/frequency?
     
  2. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    yes...but that will give you the antenna length in miles. :)

    A better rule of thumb

    1/2 wave dipole= 468/frequency(MHz)

    ERic
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    Is the lag included in that number? I thought there was a 95% (or so) difference in the speed of light in a vacumn vs. a wire.
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    Maybe closer to 96%. The antenna should be 4% shorter (I seem to recall) than the math indicates.
     
  5. ELECTRONERD

    Senior Member

    May 26, 2009
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    Or you can do 300/f (in MHz), to find the distance in meters. Yes you are correct, I'm not sure what percentage it really is but we tend to use an antenna analyzer to read the SWR and impedance of the antenna and then usually clip the ends a bit to adjust it.
     
  6. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    yes it is.....in free space it woud be 492 :)

    eric
     
  7. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
    413
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    Awsome! thanks!
     
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