[TowerTalk] Ladder Line Question?

[Wes]

I wrote about some of this in this forum back on 4/13.

BTW, my paper was never in QST but it was in Vol 6 of the ARRL Antenna 
Compendium, p. 174.  A draft copy is here: http://k6mhe.com/n7ws/Ladder_Line.pdf

Wes  N7WS


On 4/21/2019 2:36 PM, Jim Brown wrote:
> Hi Mike,
>
> I see several possible issues. Like Jim Lux, I don't trust the loss data nor 
> the measurement technique. Far better would be swept S11 measurements of a 
> known length with the far end open and shorted, and post-processing in AC6LA's 
> ZPlots. From my own experience attempting to measure paired lines, the most 
> critical part is dealing with the interface between an unbalanced analyzer and 
> the line. KN5L does this with a carefully wound transformer at the output of 
> the analyzer, with calibration performed on the output side of the transformer 
> (that is, where the line is connected).
>
> The other possible issue is absorption of rain by the foam, and it's effect on 
> characteristics of the line. Many years ago, QST published excellent work by 
> N7WS on the greatly increased loss of window line when it is wet. That piece 
> is reprinted in one of the ARRL Antenna Compendiums.
>
> 73, Jim K9YC