NAME

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


SYNOPSIS

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


WARNING

     This man page is not a complete set  of  documentation.  See
     the  html  files for more complete information. So far, I've
     not managed to install the html files  into  /usr/local,  so
     you  will  have  to  look into the atlc-X.Y.Z/docs/html-docs
     directory for them.


DESCRIPTION

     create_bmp_for_circ_in_circ is a pre-processor for atlc, the
     finite  difference  programme  that is used to calculate the
     properties of a two and three conductor electrical transmis-
     sion   line   of  arbitrary  cross  section.  The  programme
     create_bmp_for_circ_in_circ is used as a fast  way  of  gen-
     erating  bitmaps  (there  is  no need to use a graphics pro-
     gramme), for a circular conductor inside a circular  conduc-
     tor (coaxial conductors), like this:


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

     The parameter 'D' is the inner dimensions of the outer  con-
     ductor 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 dielec-
     tric of relative permittivity 'Er'.

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

     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 programme atlc does not know
     what  this  permittivity  is, so atlc, must be told with the
     command line option -d, as in example 4 below.


OPTIONS

     -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.

     -v
     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.



COLOURS

     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 in:

     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, turquiose,  sandy,  brown,  gray
     etc  may mean slightly different things to different people.
     This is not so with  atlc,  as  the  programme  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
     recognised by atlc, or you must define  it  with  a  command
     line option (see OPTIONS and example 5 below).
     The following conductors are recognised 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  programme  gets  extended to
     analyse directional couplers.

     The following dielectrics are recognised by atlc and so  are
     produced by create_bmp_for_circ_in_circ.

     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)


NOTE

     Although create_bmp_for_circ_in_circ is  used  for  circular
     inner and outer conductors, the outside of the outer conduc-
     tor 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 circle.


EXAMPLES

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

     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  cen-
     trally (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
     esitmate 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   >
     bigger_not_in_centre.bmp
     % 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 calcula-
     tions. However, the final result should be more accurate. In
     this  case,  the  result  reported is 24.2461 Ohms, an error
     that't manginally smaller than before at  0.285  %.   It  is
     possible  there may be something to be gained by decreassing
     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,   instead    of    re-directing
     create_bmp_for_circ_in_circ's  output  to  a file with the >
     sign, it is done using the -f option.
     % create_bmp_for_circ_in_circ -f 13inner_22outer_coax.bmp 22
     13 0 1.0
     % atlc 13inner_22outer_coax.bmp
     %atlc will calculate an impedance of 32.5063  Ohms,  whereas
     the  correct  value,  calculated  using  the  formula  Zo=60
     log(D/d) is 31.5656 Ohms, so altc has an error of -0.187 %.

     In the fifth example, a material with a  relativity  permit-
     tivity  7.89  of is used. While there is no change in how to
     use create_bmp_for_circ_in_circ, since this permittivity  is
     not  one  of  the  pre-defined values (see COLOURS), we must
     tell atlc what it is % 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.



SEE ALSO

     atlc(1)                       create_bmp_for_circ_in_rect(1)
     create_bmp_for_microstrip_coupler(1)
     create_bmp_for_rect_cen_in_rect(1)
     create_bmp_for_rect_cen_in_rect_coupler(1)
     create_bmp_for_rect_in_circ(1)
     create_bmp_for_rect_in_rect(1)
     create_bmp_for_stripline_coupler(1)
     create_bmp_for_symmetrical_stripline(1)    design_coupler(1)
     find_optimal_dimensions_for_microstrip_coupler(1) readbin(1)

     http://atlc.sourceforge.net                - Home page
     http://sourceforge.net/projects/atlc       - 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
     http://www.david-kirkby.co.uk              - my home page
     http://www.david-kirkby.co.uk/ham          - ham radio pages

















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