Re: NEC-LIST: 4nec2 LATEST. Patches

"Carrigan, Ken" <KCarrigan_at_anteon.com> writes:
> Paul Thanks,
> I've read about the same things somewhere on the Web, but still foreign
> to me. If only the center is used and its normal vector, sounds more
> like either a point source, or infinite spance in perpendicular
> coordinates from the vector. It would seem like the patch represents a
> perfect magnetic & electric field plate, which reflects all energy. I'm
> not seeing what the use for Patch (SP) command would apply to?

I think that NEC is really a wire modeling program. Patches are "sort of"
supported in a limited way, consistent with how it models wires (or more
properly, segments of wires). It builds a big interaction matrix
(admittances between segments) and solves a huge linear system of equations.
Patches don't really fit within this except in a sort of schematic way.

If you really need to model patches/surfaces in all their glory, other
modeling approaches are more appropriate.

> I know in the 4NEC2 there are patch examples, like Coffee, which is just
> a coffee can patch model with a dipole inside as radiator. Are we saying
> that each patch coordinate is a perpendicular vector (normal) with a
> center vector? I'm not seeing each vector/patch coordinate as a 'box'.
>
> Can someone explain this a bit better on the used for, and against a
> Patch?
>
> I'm using it to model a Table (patched) with equipment and radiators on
> it, and the legs of the table are modeled as 'wires' to the ground
> plane. If I model the table with wires, are we saving that the results I
> am getting using patches will be different then modeling with wires?
> There are examples in 4NEC2 which use Patches for modeling 3 dimensional
> structures which have radiating elements mounted on them.
>
> Any thoughts?
> v/r
> Ken Carrigan

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