On Wed,12/3/2014 3:31 PM, Roger (K8RI) on TT wrote:
Take for instance the 75 meter, center fed dipole whose impedance can
vary widely from well below 50 ohms to above 50 ohms depending on
height. You are feeding a supposedly balanced antenna with
unbalanced line. (Good place for a choke).
And it also varies widely from one end of the band to the other. We can
see this on a Smith Chart and on an SWR curve beginning around slide
#30. This particular dipole is modeled around 100 ft over average
ground, and Z at resonance is 76.5 ohms. Over lousy ground, the Z would
be in the mid- to high-80s of ohms.
http://k9yc.com/PacificonSmithChart.pdf
73, Jim K9YC
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