Re: Topband: Anyone purchased the ARRL book on Short Antennas for160???

[Jim Brown <jim@audiosystemsgroup.com>]

On 1/21/2014 5:36 PM, Tom W8JI wrote:
> When the antenna is less than 1/2 wave long, and if we do not change 
> the antenna configuration, we can move the feedline around in an 
> antenna until we turn blue and the only thing that changes is feed 
> impedance. 
AND, potentially, moving the feedpoint can change the common mode 
current on the transmission line, which WILL change more than the 
feedpoint impedance. This will depend on the line (2-wire or coax), the 
electrical length of the line, the degree of imbalance in the system, 
the orientation of the feedline with respect to the antenna, and whether 
the line is isolated on either or both ends by a choke or transformer.
73, Jim K9YC
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