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 - 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
/usr/local/share/atlc/docs/html-docs/index.html
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 http://atlc.sourceforge.net/ 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.
DESCRIPTION
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 *********** **
*** | *** ***
** | **
*<------------------------D------------------------>*
** **
** **
** **
*** ***
** **
*** ***
** **
** **
** **
*** ***
**** ****
**** ****
***** *****
****** ******
*******************
***
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
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 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.
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, 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
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 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
circle.
EXAMPLES
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
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 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.
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
Dr. David Kirkby atlc-4.4.2 10th Sept create_bmp_for_circ_in_circ(1)