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)
against
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
lengths:
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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