Spurred on by you two I have just revisited MMANA-GAL with the
simulation of my 500kHz vertical - pretty similar to your top loaded
designs but without any top loading. I have shown it resonates
(approximately at the correct frequency) and my model (attached)
shows how to add a loading coil (in my case at 1m height) and base
fed with the source.
I have now found out that all NEC models do not use the ground
characteristics in calculating impedance, they only use them for the
radiation plots. Hence you will see that mine has a resistive
impedance of 0.136 ohms which is just the radiation resistance. When
you have 50-100 plus of earth losses this will of course add to the
impedance and makes the use of the program for impedance matching and
efficiency calculations effectively useless.
73 Dave G3YMC
On 28 Dec 2007 at 18:45, Graham wrote:
> Ok Thanks for that Rik,
>
> Thats the basic layout , ive only 2 top wires , but thats the layout
> .. I see you have a load defined in the geometry listing , but where
> on the ae is it located ? , I found one post on the user group , where
> a element could be given a short lenght and have inductance added to
> it .. that way you could control where the coil was placed
>
> My ae has the 'coil' at the 90 deg bend , top of the vertical section
> , if i could work out how to add that, I would be half way there !
> the earth system would be the other half hihi
>
> Tnx
>
> Graham ..
http://www.davesergeant.com
g3ymc500kvert.maa
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