[TowerTalk] Understanding Antenna Impedance Measurements (was Foam cables and velocty factor)

Jim Brown jim at audiosystemsgroup.com
Tue Nov 15 00:26:53 EST 2005


On Mon, 14 Nov 2005 22:45:15 -0600, Robert Chudek wrote:

>So when I analyze the antenna through the feedline at 1830, the
>readings will be valid.

But you still haven't told us what the Z reading is at the low VSWR 
point, which will help us help you zero in on what's going on.  :)  

Also, the variation in wavelength between 1680 and 1830 is only 
about 10%, so the transformation is still not a LOT different from a 
half wavelength. Also, I wouldn't trust that your guess about the 
electrical wavelength in coax to tell you for certain what the 
antenna Z is. But the Z reading combined with the VSWR will help.

Jim





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