[TowerTalk] resonance/swr/impedance plots

[i4jmy@iol.it]

.
> 
> Make it longer, and a simple fixed series capacitor will take out the
> reactance and give you a 50 ohm feed point with no reactance, properly
> tuned. Further, the ground losses have been reduced by a factor of  4
> ( I squared R loss) since the current at the feedpoint is cut in half.
> The antenna is NOT resonant, as you point out, but it's BETTER. 

No, the ground losses are exactly the same they were.
Symply the highest current point (and losses) are moved away from 
antenna base so making a need to increase radials density at farther 
distance from base.
Stretching to the limit, an Half wave vertical against a ground plane 
has nearly zero current at base, but along radials the current is 
present beeing maximal one quarterwave off.

73,
Mauri I4JMY  


> 
> Regards, Guy
> Apex, NC
> 
> 
> ----- Original Message -----
> From: alsopb <alsopb@gloryroad.net>
> To: Jerry Devine <krr2ak@juno.com>; <towertalk@contesting.com>
> Sent: Wednesday, November 29, 2000 9:12 AM
> Subject: [TowerTalk] resonance/swr/impedance plots
> 
> 
> > Jerry,
> >
> > To further illustrate my point.  Min SWR is NOT ALWAYS the indicator
> > of true resonance.
> >
> > Here are two tables of data generated by EZNEC for a dipole cut to
> > resonance at 13.8 Mhz.  One assumes a reference impedance of 50 ohms
> > for SWR calculation the other assumes 200 ohms.
> >
> > Zsource               =50 ohms                                 =200
> > ohms
> > freq  13.5  z = 95.2  SWR =1.905  (complex =-33.7, real =67.7)  
3.045
> >       13.6  z = 81.5  SWR =1


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