[Antennas] Vertical impedances

Fri, 14 Mar 2003 06:48:44 -0500

Kees,

A 1/4 wave length ground plane antenna with a perfect ground at resonance 
has an impedance of 36 +j0 ohms.  If you add ground resistance, it may come 
out 50 +j0 or some other number depending on the ground resistance.  At 50 
+ j0 it will have a SWR of 1:1.  An antenna always has an impedance of J0 
ohms at resonance by definition, but not necessarily the best SWR, if the R 
component is not 50 ohms and it is measured with a SWR bridge calibrated to 
read an SWR of 1:1 with 50 +j0 ohms.

At 08:12 PM 3/13/2003 -0600, [email protected] wrote:
>Does someone have complex impedance measurements of their
>vertical (at the feedpoint) for the best SWR point in each band.
>I'd like to have something to compare to what I may be building
>and I know it's far from Z = 50 +/- j0.
>
>Trying to optimize efficiency since a lot of the power input
>does not flow through the antenna radiation resistance and
>become part of the radiated signal.
>
>73  Kees K5BCQ
>- - -
>
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73, Chas, W1CG
K2 #462