Re: NEC-LIST: How can I use the currents in the out files ot computefar filed?

On 10/24/09 9:14 AM, "张小林" <xlzhang0606_at_163.com> wrote:

> I am so grateful to receive quick replies from Lux, Jerry and Phil.
> Initially, I just wonder to know how I can use the currents in the out files
> ,so I take an array of dipoles as an example. Actually, I am dealing with a
> sector array of horizontal polarized traveling-wave antennas at HF band. The
> element is a direcitonal antenna, with a 30-60 degrees beamwidth. I don't
> know much about antenna couplings. Whant I want to do is just to see how
> the element's pattern differs from its own pattern when used alone. If the
> difference is tolerable, we can neglect the couplings between elements and
> use their own patterns.

If the dipoles are less than a wavelength apart, there will be significant
coupling. This sort of antenna ( an array of closely spaced dipoles) is a
good example where "element pattern" multiplied by "array pattern for
isotropic radiators" doesn't work very well.

Well, maybe not totally.. It does work, but the problem is that the
feedpoint currents (magnitude and phase) probably won't be what you expect
if you're using a simple feed network (because of the substantial mutual
coupling).

Pretty much any antenna textbook goes into this in a fair amount of detail.
There's even one online from Orfanidis and he has matlab code on the website
to do a lot of what you want to do.
http://www.ece.rutgers.edu/~orfanidi/ewa/

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