Re: NEC-LIST: Crossing of wire segements

In my experience, crossed segments can produce anything from mildly
wrong results to bizarrely wrong results, and sometimes negative source
resistance and power or a program crash. I'd guess that you might be
able to get away with it if the currents in the crossing segments is
very small -- but then you could just remove the segments from the model
with little effect.

Maybe someone else can give you an answer that's closer to what you'd
like to hear, but I'd never trust results from a model with crossing
segments.

Roy Lewallen

Rian Sanderson wrote:
> How firm is the crossing of segments restriction in NEC-2? From page 9 of
> the NEC manual it states:
>
> "Segments (or patches) may not overlap since the division of current
> between two overlapping segments is indeterminate. Overlapping segments
> may result in a singular matrix equation."
>
> I took this to mean: if segments cross the simulation probably won't be
> able to compute. If it can compute, it will.
>
> I hope it doesn't mean what it probably does: crossing segments leads to a
> completely invalid simulation.
>
> I've used genetic programing and NEC-2 to synthesize an antenna. My approach
> minimizes crossed segements, but they still ocurred in my final results. I
> want to know if my results are valid. I'd replace the junction by hand with
> more segments, but I'm already at the minimum suggested segment size for my
> wire radius and excitation frequency.
>
>
> Thanks for you help,
>
> Rian Sanderson
>

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