Re: NEC-LIST: loop antenna

 From Lutz Pascale:
>
>Here is the input file :
>
>CE loop
>GH 1 101 0 0 0.5 0.5 0.5 0.5 0.01
>GE
>FR 0 1 0 0 50 0.
>EK
>PQ
>LD 4 1 2 2 100
>LD 4 1 101 101 100
>EX 0 0 1 0 1
>NE 0 1 21 21 0. -10 -10 0. 1 1
>NE 0 21 1 21 -10 0. -10 1 0. 1
>NH 0 1 21 21 0. -10 -10 0. 1 1
>NH 0 21 1 21 -10 0. -10 1 0. 1
>XQ
>EN
>
>Here is the error message in the input file :
>
> - MULTIPLE WIRE JUNCTIONS -
> JUNCTION SEGMENTS (- FOR END 1, + FOR END 2)
> CONNECT - SEGMENT CONNECTION ERROR FOR SEGMENT 31

The first problem that I encountered with this data is that it is
typed with tabs. The version of NEC-2 here cannot read that, but
there may be some around that will. Also, the standard NEC-2 will not
take a GH command with the helix length (2nd real parameter) equal to
zero. GH was not part of the basic NEC-2 and is not in the NEC-2
manual. It was added later without much checking, and the code
divides by zero when helix length is zero. I get a bunch of NaNs from
this data.

You can make a loop with the GA command for an arc. To take advantage
of symmetry with N segments the arc angle would be 360/N and a "GR 0
N" (N <= symmetry dimension limit) command would complete the loop,
but that does not help if ground or other interactions destroy the
symmetry. There is no easy way to generate a flat spiral in a NEC-2
code with this GH problem, although a length that is small but not
quite zero might work well enough.

Jerry Burke
LLNL
Received on Sat Sep 16 2000 - 16:36:30 EDT