Re: NEC-LIST:Modeling a conductive surface in NEC2

In my previous e-mail I mentioned that you can model any surface using wire
segments in NEC. By that I meant any metal surface of course.

> Hi Jerry
>
> You can model any surface using wire segments that are about a 1/10 of a
> wavelength in length.
> I don't think that the diameter of the wires would be of such importance
in
> such a case as long as they satisfy the general rules for NEC with regards
> to Segment length to radius ratios etc.
> This same technique of modeling surfaces by a wire mesh can even be used
to
> model very complex structures such as aircraft, boats, cars etc.
>
> If you are looking for a easy to use, professional program to quickly
model
> this problem, why don't you try using SuperNEC. It has a full 3D graphical
> interface so you won't have to write any text .nec files, and a really
great
> output interface for plotting 3D radiation patterns, smith chart plots etc
> etc. It also has a number of predefined structure and antenna assemblies
> such as wire mesh plates, cylinders, spheres, yagi's, helices, lpda's etc
> etc. With the antenna assemblies, by changing your model frequency in
> SuperNEC, the assemblies are automatically re-segmented so that your model
> remains valid. Another great feature of this product is the structure
> checker which checks your model to see that all the nec rules to produce
> accurate results have been followed.
> I am sure that these features of SuperNEC will considerably reduce the
time
> taken to model your specific problem.
>
> You can download SuperNEC from www.supernec.com and get a 30day evaluation
> license file for running the software.
>
> Regards
> Brandon Orchard
> ----- Original Message -----
> From: "Jerry Flanders" <jeflanders_at_comcast.net>
> To: <nec-list_at_gweep.ca>
> Sent: Friday, September 27, 2002 11:42 PM
> Subject: NEC-LIST:Modeling a conductive surface in NEC2
>
>
> > I am trying to evaluate a few ideas for a replacement antenna for my
ham
> > radio club's 2 Meter repeater.
> >
> > The new antenna will be mounted on one of our city's water tanks. I
would
> > like to take into account the effect of this nearby reflective surface
in
> > the model calculations.
> >
> > I understand NEC2 cannot model the surface, but that I can simulate the
> > surface with a wire grid. I need help with some specifics on the grid
> > structure.
> >
> > I have a copy of Arie's "Build" to actually generate a grid of the right
> > size and shape, but I don't know what mesh size (size of the openings)
is
> > appropriate. If I use too large a mesh opening, I suspect it would not
> > represent a plane surface accurately, but if I just use an
> > arbitrarily fine mesh, I will cripple this 384MB computer. Is there a
> rule
> > of thumb for adequate mesh "pore" sizes in terms of wavelength?
> >
> > I could also use advice on what diameter "wire" to use for the grid, and
> > what conductivity, if conductivity is important. I assume it is a steel
> tank.
> >
> > Anybody?
> >
> > Jerry Flanders
> >
> > W4UK
> > --
> > The NEC-List mailing list <nec-list_at_gweep.ca>
> > http://www.gweep.ca/mailman/listinfo.cgi/nec-list
>

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