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       create_bmp_for_circ_in_circ  -  bitmap generator for circular conductor
       inside circular conductor (part of atlc)


       create_bmp_for_circ_in_circ [options... ] D d O Er filename.bmp


       This man page is not a complete set of documentation -  the  complexity
       of  the  atlc  project makes man pages not an ideal way to document it,
       although out  of  completeness,  man  pages  are  produced.   The  best
       documentation  that  was  current  at the time the version was produced
       should be found on your hard drive, usually at
       although it might be elsewhere if your system  administrator  chose  to
       install  the  package elsewhere. Sometimes, errors are corrected in the
       documentation and placed at before  a  new
       release  of atlc is released.  Please, if you notice a problem with the
       documentation - even spelling errors and typos, please let me know.


       create_bmp_for_circ_in_circ is a pre-processor  for  atlc,  the  finite
       difference  program  that  is used to calculate the properties of a two
       and three conductor electrical transmission  line  of  arbitrary  cross
       section.  The program create_bmp_for_circ_in_circ is used as a fast way
       of generating bitmaps (there is no need to use a graphics program), for
       a  circular conductor inside a circular conductor (coaxial conductors),
       like this:

                       ****                 ****
                    ****    <-----d------>     ****
                  ***            *****            ***
                ***           ***********           ***
              ***            *************            ***
             ***            ***************            ***
            ***      ^      ***************             ***
           ***       |      ***************              ***
          ***        |       *************                ***
          **         O        ***********                  **
         ***         |            ***                      ***
         **          |                                      **
         **                                                 **
         **                                                 **
         **                                                 **
         ***                                               ***
          **                                               **
          ***                                             ***
           **                                             **
            **                                           **
             **                                         **
              ***                                     ***
               ****                                 ****
                 ****                             ****
                   *****                       *****
                      ******               ******

       The parameter ’D’ is the inner dimensions of the  outer  conductor  and
       ’d’  is the outer diameter of the inner conductor.  The inner conductor
       is offset ’h’ from the centre of the outer conductor. The whole  region
       is surrounded by a dielectric of relative permittivity ’Er’.

       The  bitmap  is  printed  to  ’outfile.bmp’  -  the  last  command line

       The bitmaps produced  by  create_bmp_for_circ_in_circ  are  24-bit  bit
       colour bitmaps, as are required by atlc.

       The permittivities of the dielectric ’Er’ determines the colours in the
       bitmap. If Er is 1.0, 1.006, 2.1, 2.2, 2.33, 2.5, 3.3, 3.335, 3,7, 4.8,
       10.2 or 100, then the colour corresponding to that permittivity will be
       set according to the colours defined in COLOURS below. If Er is not one
       of  those  permittivities, the region of permittivity Er will be set to
       the  colour  0xCAFF00.  The  program  atlc  does  not  know  what  this
       permittivity is, so atlc, must be told with the command line option -d,
       as in example 4 below.


       -b bitmapsize
       is used to set the size of the bitmap, and so  the  accuracy  to  which
       atlc  is  able  to  calculate  the  transmission line’s properties. The
       default value for ’bitmapsize’ is normally 4, although this is  set  at
       compile time. The value can be set anywhere from 1 to 15, but more than
       8 is probably not sensible.

       -f outfile
       Set the output filename. By default, the bitmap is sent to stdout,  but
       it *must* be sent to a file, with this option, or as described above.

       Causes  create_bmp_for_circ_in_circ to print some data to stderr. Note,
       nothing extra goes to standard  output,  as  that  is  expected  to  be
       redirected to a bitmap file.


       The 24-bit bitmaps that atlc expects, have 8 bits assigned to represent
       the amount of red, 8 for blue and 8 for  green.  Hence  there  are  256
       levels  of  red, green and blue, making a total of 256*256*256=16777216
       colours.  Every one of the possible 16777216  colours  can  be  defined
       precisely  by  the  stating the exact amount of red, green and blue, as

       red         = 255,000,000 or 0xff0000
       green       = 000,255,000 or 0x00ff00
       blue        = 000,000,255 or 0x0000ff
       black       = 000,000,000 or 0x000000
       white       = 255,255,255 or 0xffffff
       Brown       = 255,000,255 or 0xff00ff
       gray        = 142,142,142 or 0x8e8e8e

       Some colours, such as pink, turquoise, sandy, brown, gray etc may  mean
       slightly  different  things  to  different  people. This is not so with
       atlc, as the program expects the colours below to be EXACTLY defined as
       given. Whether you feel the colour is sandy or yellow is up to you, but
       if you use it in your bitmap, then it  either  needs  to  be  a  colour
       reconised  by  atlc,  or  you must define it with a command line option
       (see OPTIONS and example 5 below).
       The following conductors are reconised by atlc:
       red    = 255,000,000 or 0xff0000 is the live conductor.
       green  = 000,255,000 or 0x00ff00 is the grounded conductor.
       blue   = 000,000,000 or 0x000000 is the negative conductor

       All bitmaps must have the live (red) and  grounded  (green)  conductor.
       The  blue  conductor is not currently supported, but it will be used to
       indicate a negative conductor, which will be needed if/when the program
       gets extended to analyse directional couplers.

       The  following dielectrics are reconised by atlc and so are produced by

       white     255,255,255 or 0xFFFFFF as Er=1.0   (vacuum)
       pink      255,202,202 or 0xFFCACA as Er=1.0006 (air)
       blue      000,000,255 or 0x0000FF as Er=2.1   (PTFE)
       Mid gray  142,242,142 or 0x8E8E8E as Er=2.2   (duroid 5880)
       mauve     255.000,255 or 0xFF00FF as Er=2.33  (polyethylene)
       yellow    255,255,000 or 0xFFFF00 as Er=2.5   (polystyrene)
       sandy     239,203,027 or 0xEFCC1A as Er=3.3   (PVC)
       brown     188,127,096 or 0xBC7F60 as Er=3.335 (epoxy resin)
       Turquoise 026,239,179 or 0x1AEFB3 as Er=4.8   (glass PCB)
       Dark gray 142,142,142 or ox696969 as Er=6.15  (duroid 6006)
       L. gray   240,240,240 or 0xDCDCDC as Er=10.2  (duroid 6010)


       Although create_bmp_for_circ_in_circ is used  for  circular  inner  and
       outer  conductors,  the  outside  of  the outer conductor is drawn as a
       square. This  is  for  convenience  and  makes  no  difference  to  the
       calculations.  The  inside  is  of  the  outer  conductor is drawn as a


       Here are a few examples  of  the  use  of  create_bmp_for_circ_in_circ.
       Again,    see   the   html   documentation   in   atlc-X.Y.Z/docs/html-
       docs/index.html for more examples.

       1) In the first example, the outer conductor has an inside diameter  of
       12  units (inches, mm, feet etc.), the inner has an outside diameter of
       3.9 units.  The inner is placed centrally (h=0) and the  dielectric  is
       vacuum (Er=1.0).
       % create_bmp_for_circ_in_circ 12 3.9 0 1.0 coaxial_1.bmp
       % atlc coaxial_1.bmp
       atlc  will  indicate the correct value of impedance to be 67.3667 Ohms,
       whereas an exact analysis will show the true value to be 67.4358  Ohms,
       so atlc has an error of 0.102%.

       2)  In  this  second  example,  the conductor sizes are the sames as in
       example 1, but the inner  is  located  3.5  units  off-centre  and  the
       dielectric  has  a relative permittivity of 2.1 (Er of PTFE) The output
       is sent to a file not_in_centre.bmp which is then processed by atlc
       % create_bmp_for_circ_in_circ 12 3.9 3.5 2.1 not_in_centre.bmp
       % atlc not_in_centre.bmp
       The  impedance  of   this   is   theoretically   24.315342   Ohms,   as
       create_bmp_for_circ_in_circ  will calculate for you. atlc’s estimate is
       24.2493 Ohms, an error of only -0.271 %.

       3) In the  third  example  the  bitmap  is  made  larger,  to  increase
       accuracy, but otherwise this is identical to the previous one.
       %     create_bmp_for_circ_in_circ     -b8     12     3.9     3.5    2.1
       % atlc bigger_not_in_centre.bmp
       This time atlc will take much longer to calculate Zo, since the  bitmap
       is  larger  and so it needs to do more calculations. However, the final
       result should be more accurate. In this case, the  result  reported  is
       24.2461  Ohms,  an error that’s marginally smaller than before at 0.285
       %.  It is possible there may be something to be  gained  by  decreasing
       the  cutoff  at  larger  grids, so this is being investigated. However,
       errors almost always below 0.25 %, no matter what is being analysed.

       In the fourth example, a material with a relativity  permittivity  7.89
       of    is    used.    There    is    no    change    in   how   to   use
       create_bmp_for_circ_in_circ, but since this permittivity is not one  of
       the  pre-defined  values  (see  COLOURS), we must tell atlc what it is.
       The  colour  will  be  set  an  olive  green  one,  with  a  hexacidcal
       representation  of  red=0xCA,  blue=OxFF  and  green  = 0x00. This just
       happens to be  the  default  colour   used  when  the  permittivity  is
       unknown. So atlc must be given this information, like thisL
       % create_bmp_for_circ_in_circ 23 9 0 7.89 an_odd_er.bmp
       % atlc -d CAFF00=7.89 an_odd_er.bmp This has a theoretical impedance of
       20.041970 Ohms, but atlc version 3.0.1 will calculate it to be 20.0300,
       an  error  of -0.058 % !!! If you look at the file an_odd_er.bmp with a
       graphics package, you will see there are 3 colours  in  it  -  the  red
       inner conductor, the green outer and an olive-green dielectric.


       design_coupler(1)     find_optimal_dimensions_for_microstrip_coupler(1)
       readbin(1)                - Home page       - Download area
       atlc-X.Y.Z/docs/html-docs/index.html       - HTML docs
       atlc-X.Y.Z/docs/qex-december-1996/atlc.pdf - theory paper
       atlc-X.Y.Z/examples                        - examples

Dr. David Kirkby           atlc-4.4.2 10th Sept create_bmp_for_circ_in_circ(1)