 		        	DOC


 Documentation of "npp", the NEC2 post processor for Linux

Antenna files are all in the directory Antenne; the results of the computations
go into the directory Risultati.

The post processor is run from X-windows:
Open a terminal windows and cd to the main directory (e.g. /usr/local/nec2)

From this position you can give the command

  >             nec file_name

for computing the antenna described in Antenne/file_name.nec

or you can give the command

  >              npp file_name

to post-process the file Risultati/file_name.out

The effect of the command "nec" is to call NEC2 main program which produces
the file .out in the Risultati directory and, than to call "npp" to do the
post-processing. The post-processing produces nice diagrams in X-windows and
the file file_name.ps in the directory Risultati.

The diagrams windows remain for few minutes on the sceen than disappears.
If you press Ctrl-C you can kill the diagrams windows earlier.
 (Please help to improve this part !!)


The Post Script file can be further reviewed with Ghostview and eventually
printed. (of course you must have properly configured your Linux to handle
Post Script files !!)


The file_name.nec is supposed to describe the antenna as in MiniNEC:
       The main direction of radiation is along the x-axis.

The file_name.nec file must contain a line of instruction for npp in orther
to make npp do its duty.

This line is for NEC2 a comment line.
It has the form:

	     CMPP  x, a, b, c, d

and it is in perfect cryptic nec2 format.

...  x  says the kind of post-process to be done,
     a  says the kind of diagram required,
      b, c, d  are switches to qualify x (not yet used in version 1.1 )

At present, (version 1.1), npp knows only 4 values for x:

      0   no post-processing
      1   for antennas in free space
      2   for antennas over ground
      3   for frequency sweep of antennas in free space

The absence of the CMPP line or x=0 stops the post-processor.

The value of a can be:

      0   Cartesian plot
      1   Polar linear
      2	  Polar ARRL relative

In orther to make the post-processor to work it is compulsory to have
the proper RP lines in the .nec file !!!!!!

For x=1, i.e. antennas in free space, there must be the following  lines:

PT -1
RP  0, 1, 1,  1001, 90, 0, 0, 0
RP  0, 1, 1,  1001, 90,180, 0, 0
RP  0, 1, 361, 1001, 90, 0, 1, 1
RP  0, 361, 1, 1001, 0, 0, 1, 1


For x=2, i.e. antennas over ground, there must be the following  lines:

PT -1
RP  0  181   1 1001  -90.00  0.0  1.0  0.0 1.00E+04 0.00E+00


For x=3 i.e. for frequency sweep of free space antennas

FR  0,21,0,0, 28.0,0.1
....

PT -1
RP  0, 1, 1,  1001, 90, 0, 0, 0
FR  0,21,0,0, 28.0,0.1
RP  0, 1, 1,  1001, 90,180, 0, 0

The FR cards can be modified in accord to the antenna:
  In the example 21 is the number of steps,
		 28.0 is the starting frequencyin MHz
		 0.1  is the step in MHz

 The RP cards must be the same.



  Happy computing de     Pino    i2kfx@amsat.org



