Re: NEC-LIST:Question about the plate in SuperNEC

Dear Jianxu

As Scott Townley and Chuck Counselman wrote a couple of weeks ago, a solid
conductive surface can be modelled by a wire mesh with radius set such that
the perimeter (2*pi*r) of a segment equals the center-to-center spacing
between adjacent sgements.

This is why when your segment length is set to 0.1m that SuperNEC
automatically sets the diameter to 30mm in the snplate assembly.

Your segment length is also not to long otherwise SuperNEC would have given
errors in the structure checker.

Generally for antenna structures your segment length should be about 0.1 of
a wavelength but you should still get pretty good results if your segment
length is between 0.2 to 0.001 of a wavelength, making sure that your
segment length to radius rules are still maintained (you can find all the
segment length, radius....rules in the SuperNEC help files).

For the plate you are simulating, you can try increasing the segmentation
(it may increase your accuracy) by setting your model frequency higher in
SuperNEC, this will however also increase your simulation time (as
expected-more segments).

Regards
Brandon Orchard

----- Original Message -----
From: "jianxu" <jianxu_at_ee.ualberta.ca>
To: <nec-list_at_gweep.ca>
Sent: Monday, November 18, 2002 6:30 PM
Subject: NEC-LIST:Question about the plate in SuperNEC

> When I use SuperNEC to simulate my antenna (operates at 144Mhz) which is
> 5cm away from a plate, I found that the default diameter setting for wire
> segments used to construct the plate is about 30mm when the segment length
> is 0.1m. I changed the wire diamater from 30mm to 2mm and the simulation
> results (antenna impedance, coupling etc) are quite different from the
> actual measured one. When I use the default 30mm setting the simulation
> results are closer to the actual measured values. Is there any particular
> reason to use such thick wire segments to construct a plate? Does it mean
> that the wire segment length of 0.1m is too long for 144Mhz? I think 0.1m
> should be short enough for 144Mhz and the software does not give me any
> warning either.
> --
> The NEC-List mailing list <nec-list_at_gweep.ca>
> http://www.gweep.ca/mailman/listinfo.cgi/nec-list

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