[TowerTalk] The Antenna System

[Steve Hunt]

Tod,

Good points!

I originally used a Log scale for the Y axis but it couldn't handle the 
change in sign of the reactance, which of course is critical to the 
discussion. In the end I opted for Linear on the basis that, for choke 
discussions, we're not really interested in the detail when impedances 
are below a few hundred Ohms :)

73,
Steve G3TXQ



On 22/04/2012 03:47, Tod Olson wrote:
>
> The graph that Steve, G3TXQ, made available really was interesting to study.
> One could look at it and see the effect of going from a feed line coax
> length of 1?4 wavelength to 1?2 wavelength to 3/4 wavelength. Adding the
> common mode reactances to the CM choke reactance provided the red line
> showing the net impedance of the CM path.
>
> I might suggest that he add a note about the CM Choke impedance he used
> since that was incorporated into the net impedance (Zcm) he was showing. The
> Rcm at 0.5 wavelengths looks like it is zero, but that is because the scale
> of the graph is ?4000 to +8000 ohms and resistances of say, 100 ohms,  will
> look like zero.
>
>