Re: NEC-LIST: Modeling an EMP using NEC

Quoting justin.mckinnerney_at_l-3com.com, on Sun 25 May 2008 05:38:52 PM PDT:

> All,
>
> I'm trying to model an EMP using NEC in order to calculate the coupling
> to an antenna. I was just wondering if anyone had any suggestions on
> how to go about doing this? Thanks for any help you can provide.
>
> Regards,
> Justin L. McKinnerney
>
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There are several nice papers out there dealing with modeling the
effects of lightning using NEC.

Since NEC is basically a single frequency modeling program, what you
do is model the system at a bunch of systematically chosen
frequencies. That gives you the "frequency response" of the system.
THen, you take the EMP impulse and transform it to frequency domain.
Do the convolution by multiplying the frequency domain EMP with the
frequency domain antenna system response, then reverse transform the
product to get the time domain antenna system output.

Check out Pokharel, Ishii, and Baba, "Numerical Electromagnetic
Analysis of Lightning Induced VOltage over Ground of Finite
Conductivity", IEEE Trans EMC, V45, #4, Nov 2003

Ishii, Baba, "Advanced Computational Methods in Lightning Performance"
, IEEE 2000 ( Might be a conference pub.. I forgot to put the journal
title in the file)

Jim

James Lux, P.E.
Flight Communications Systems Section
Jet Propulsion Laboratory
Pasadena CA 91109
+1(818)354-2075

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