X N E C V I E W
---------------
A program for visualizing NEC2 input and output data (Unix/X-windows).

Copyright (C) 1998-2001, Pieter-Tjerk de Boer

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This program is free software; you can redistribute it and/or modify
it under the terms of version 2 of the GNU General Public License as
published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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COMPILING:
----------
This should be trivial on Linux systems: just type 'make' in the
directory where the source has been unpacked.
I also supplied an Imakefile, which might make compilation on other
systems easier: typing 'xmkmf' will generate a Makefile, which can then
be used by 'make'.
Furthermore, you might want to change a few of the #define lines in config.h,
to suit your tastes; see the comments.

If the PNG library is not installed on your system, you should either
- use the Makefile after deleting the 'PNG=yes' line in it
or
- use xmkmf after doing   mv Imakefile_nopng Imakefile
Obviously, a thus-compiled version of xnecview cannot export to PNG files.

If you get an error about missing getopt.h while compiling, put a line
  #define NO_GETOPT
at the beginning of xnecview.c . You'll lose the support for command line
options, though.
This apparently happens if you have a non-GNU (compatible) version of getopt.
Perhaps I should re-implement the command line option processing using
non-GNU functions; feedback about this issue would be welcome.

Last but not least, note that xnecview needs version 1.2 or later of the
GTK+ libraries.

USAGE:
------
Just invoke xnecview with, as its command-line arguments, one or more names
of files containing NEC2 input (structure of an antenna model) and/or output
data (impedance, radiation pattern). Then xnecview will try to graphically
display whatever data is in those files, in one or two windows.
Window 1 shows a 3D plot of the structure (wires etc.) of the antenna,
and/or the spatial distribution of the radiation, and/or distribution of
the current and on the antenna elements and near electric and magnetic
fields.
Window 2 shows a set of graphs of several quantities (SWR, gain, etc.)
as a function of frequency.
Keyboard and mouse can be used to manipulate these views and export them
as postscript files.
For more details, see the manpage (i.e., the file xnecview.1x).

WHAT'S NEW:
-----------
This is version 1.31, which contains only some minor improvements 
compared to version 1.30; notably:
- changed axes of frequency plots: number of subdivisions can now be
  variable, resulting in a more readable axis (stepsizes are now always
  multiples of 1, 2, 2.5, or 5; no longer 4 or 7.5).
- impedance (Z0) can now have up to 4 digits (instead of 2)
- new option: -aupdate to set the update interval of animation
For more details, see the file HISTORY.

HELP NEEDED:
------------
I'd like some help with the following issues:
- GH-cards (helix/spiral) with helix-length = 0. I don't understand these,
  and neither does my copy of NEC. According to doc on the WWW, this is a
  non-official extension, but I'd still like to support it.
- What should be the 0 dB gain reference in the gain plots if gain data
  is available at more than one frequency? At present, the maximum gain
  observed over all frequencies is used for this; this can be handy for
  comparing gain at different frequencies, but not necessarily for
  judging the radiation pattern at one particular frequency, due to the
  non-linearity of some of the gain scales.
- In a similar vain: should the currents distribution use the same scaling
  at all frequencies if currents are available at several frequencies?
  At present, the scaling is performed separately for every frequency.
- As should be clear from the man page, the interpretation of the currents
  display is somewhat non-trivial. Hints on how to make this clearer (either
  in the documentation, or by changes to the program) would be welcome.


Contributions, comments and bug reports are welcome, please send them to
any of these addresses:
     Internet e-mail: pa3fwm@amsat.org
Amateur packet-radio: PA3FWM @ PI8DAZ.#TWE.NLD.EU

