[antennaware] Q: Extended Double Zepp with tuner and open wir e feeders

Wintheiser, Patrick Patrick.Wintheiser@PSS.Boeing.com
Wed, 11 Nov 1998 16:35:56 -0800

Thanks to all who so kindly found time to reply to my dumb questions.  I
wish the answer was obvious to me but it ain't exactly so.  I do understand
what's happening with the extended zepp now.
  As to the open wire feeders on the 1/2 wave dipole. I ran AO(mininec)
a half wave dipole, 1 wavelength high over average ground and created a
feedline with 1" spacing. 
 If resonance is defined when reactance = 0,  I could not achieve resonance
on the diplole for the frequency dimensioned(len=480/f), either with
feedline of 240/f or 480/f.  I was only able to get resonance with a feed
length of 540/f, which was not expected !.
  Following are tables showing approximate resonance points for design
f=3.75 Mhz,  with 1" spacing on feedline,  #12 wire for various feed

         feed len = 240/f
   f=2.55,  Z=10
   f=5.4  ,  Z=70

         feed len =480/f
   f=1.75,  Z=4.7
   f=4.0,    Z=82
   f=6.6  ,  Z=42
         feed len =540/f
   f=1.55,  Z=4
   f=3.75,  Z=79
   f=6.0  ,  Z=45  

Note: When I model this dipole as a standard 1 wire antenna,  only 1
resonance point is returned-at the frequency of design.
I hope I haven't becaome a nuisance with my off the wall questions.  I'm
looking to be illuminated !!!
    Pat W0OPW


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