# Re: Inductance calculation

Uwe Keller ([email protected])
Tue, 18 Feb 1997 09:20:18 +0100 (MET)

Hi,

just have a question with regard to Howard Johnsons email. He wrote

> ...
> If you are interested in the loss effects of the
> eddy currents, you will also need an approximation for the
> current distribution under the wire:
>
> j(x) = (1/(pi*h))*(1/(1 + (x/h)**2))
>
> where all current in the ground plane flows parallel to the wire
> where the ground plane is oriented parallel to the earth, and the sun is at
> high noon
> ...

To my understanding the current distribution in a plane goes somehow
with the square root, since it is proportional to the distance and related
to the singular behaviour of the fields at the edges. In particular, it seems
to represent the charge distribution in the cross--section of the conducting
sheet. I also feel the need to replace the "+" in the denominator by a minus
sign, and to introduce a constant C to be determined due to excitation.
So the formula should look like

j(x) = (C/(pi*h))*(1/sqrt(1 - (x/h)**2))

But possibly i'm wrong because i couldn't make something out of

> where the ground plane is oriented parallel to the earth, and the sun is at
> high noon

which i suppose shall define a coordinate system. Can anybody help me?

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