[600MRG] top loading

[Eric NO3M]

Yes, I was not considering the inductor losses.

However, I wonder if, in Andy's particular case, he is at or nearly at 
the point of transitioning to ground improvements to get the most "bang 
for the buck" with additional wire?

Re-modeling a 30 ft monopole with 600ft of toploading (4x150), I get 
0.381 - j251.4.  It would take 85 uH to resonate.  This is close to 
Andy's actual 82uH.

A 30ft monopole with 1350ft of toploading (4x ~338) is 0.409 - j37.21, 
taking 13 uH to resonate, or about 15% of his current inductance (38% 
number of turns).  In the case of say a 6x6 in. coil, that's going from 
approx. 28 turns to 11 turns.  Of course, it depends on the coil's 
construction (Q, etc.), but will it really make that much difference in 
coil loss reduction at these relatively low inductances?

Thanks for your work on the subject.  I need to do some additional reading.

73 Eric NO3M / WG2XJM

On 10/12/2017 04:00 PM, Rudy Severns wrote:
> I think Eric has missed an important point.
>
>   
>
> True, top-loading only marginally improves Rr but that's not the main point
> of top loading, at least on 630m.  What the top-loading does it greatly
> reduce the size of the tuning inductor.  In our small antennas the loss in
> the tuning inductor is often the dominant loss.  Top-loading improves
> efficiency by reducing loss in the tuning inductor.  I have carefully
> explained and justified that point in my LF-MF antenna notes on my web site.
>
>
>   
>
> At some point of course the inductor loss gets low enough and you have to
> get to work on the ground loss.
>
>   
>
> 73, Rudy N6LF
>