create_bmp_for_microstrip_coupler - bitmap generator for microstrip
coupler (part of atlc)
create_bmp_for_microstrip_coupler [-b bmp_size] [-v] w s g h t Er1 Er2
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 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.
create_bmp_for_microstrip_coupler is a pre-processor for atlc, part of
atlc properties of a two and three conductor electrical transmission
line of arbitrary cross section. The program
create_bmp_for_microstrip_coupler is used as a fast way of generating
bitmaps (there is no need to use a graphics program), for microstrip
couplers. Hence if the dimensions of a coupler are known the odd mode,
even mode, differential mode and common mode impedances can be found.
If you know what impedances you require and want to find the
dimentions, then use find_optimal_dimensions_for_microstrip_coupler
instead. This makes repeated calls to
create_bmp_for_microstrip_coupler. The structure for which bitmaps are
generated by create_bmp_for_microstrip_coupler is shown below.
G G |
G G |
G G |
G G |
G G |
G G |
G | G |
G | G |
G | G H
G v <--g--><--w--><---s---><--w--><--g--> G |
GGGGGGGGGG ccccccc ccccccc GGGGGGGG |
G.|t.Dielectric, permittivity=Er2.......h.............G |
G.|...(3.7 for FR4 PCB).................|.............G |
The parameters ’W’ and ’H’ and the inner dimensions of the a metal
enclosure. These will generall be quite large compared to the
dimensions of the the PC - the diagram above is not to scale. The gap
between the two coupled lines is s, the width of the coupled lines is w
and the spacing between the edges of the coupled lines and the
groundplane on the top is g. Often, the upper groundplane is not close
to the coupled lines, in which case g will be quite large. The
thickness of the dielectic is h. Note that he is just the dielectric,
and does not include the thichkness of the copper on the double-sided
PCB. The thickness of copper on the top layer is t. It is immaterial
what the thickkness of the lower layer is. The relative permittivity
above the dielectric is normally 1, but the relative permittivity of
the dielectric material will need to be either pre-defined or defined
on the command lines. See the section colours below for more
information on dielectrics.
The bitmap is printed to the file specified as the last argument
The bitmaps produced by create_bmp_for_microstrip_coupler are 24-bit
bit colour bitmaps, as are required by atlc.
The permittivities of the bitmap, set by ’Er1’ and ’Er2’, determine the
colours in the bitmap. If Er1 or Er2 is 1.0, 1.0006, 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 Er1 is not one of those permittivities, the region of
permittivity Er1 will be set to the colour 0xCAFF00. If Er2 is not one
of those values, then the region of the image will be set to the colour
0xAC82AC. The program atlc does not know what these two permittivites
are, so they atlc, must be told with the comand line option -d, as in
example 4 below.
-C Causes create_bmp_for_microstrip_coupler to print copyright and
licensing information. -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.
Causes create_bmp_for_microstrip_coupler 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
recognised by atlc, or you must define it with a command line option
(see OPTIONS and example 5 below).
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 0x0000FF 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 recognised 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)
L. blue 130,052,255 or 0x8235EF 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 0x696969 as Er=6.15 (duroid 6006)
L. gray 240,240,240 or 0xDCDCDC as Er=10.2 (duroid 6010)
D. orange 213,160,067 or 0xD5A04D as Er=100.0 (mainly for test
Here are a few examples of the use of
create_bmp_for_microstrip_coupler. Again, see the html documentation in
atlc-X.Y.Z/docs/html-docs/index.html for more examples.
In the first example, there is just an air dielectric, so Er1=Er2=1.0.
The inner of 1x1 inches (or mm, miles etc) is placed centrally in an
outer with dimensions 3 x 3 inches.
The exact place where the dielectric starts (a) and its width (d) are
unimportant, but they must still be entered.
% create_bmp_for_microstrip_coupler 3 3 1 1 1 1 1 1 > ex1.bmp
% atlc ex1.bmp
In this second example, an inner of 15.0 mm x 0.5 mm is surrounded by
an outer with internal dimensions of 61.5 x 20.1 mm. There is a
material with permittivity 2.1 (Er of PTFE) below the inner conductor.
The output from create_bmp_for_microstrip_coupler is sent to a file
ex1.bmp, which is then processed by atlc
% create_bmp_for_microstrip_coupler 61.5 20.1 5 22 0.5 50 15 5 1.0 2.1
% atlc ex2.bmp
In example 3, the bitmap is made larger, to increase accuracy, but
otherwise this is identical to the second example. %
create_bmp_for_microstrip_coupler -b7 61.5 20.1 5 22 0.5 50 15 5 1.0
2.1 > ex3.bmp
% atlc ex3.bmp
In the fourth example, materials with permittivites 2.78 and 7.89 are
used. While there is no change in how to use
create_bmp_for_microstrip_coupler, since these permittivities are not
known, we must tell atlc what they are. %
create_bmp_for_microstrip_coupler 61 20 1 4 22 0.5 50 15 5 2.78 7.89 >
ex5.bmp % atlc -d CAFF00=2.78 -d AC82AC=7.89 ex5.bmp In the sixth and
final example, the -v option is used to print some extra data to stderr
atlc(1) create_bmp_for_circ_in_circ(1) create_bmp_for_circ_in_rect(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 10thcreate2bmp_for_microstrip_coupler(1)