I've dug up another of my old programs that I though might be
of interest. It does the following:
=============================================================================
/*
Program Coax by Tom Giovannini:
08/01/91: Initial Release.
This programs contructs a Spice model for coaxial cable which provides
for skin-effect loss. It uses the loss network derived by Yen (Proc.
IEEE, Vol. 70, No. 7, July, 1982) in conjunction with the equivalent
circuit topology derived by Groudis (IBM J. Res. Dev., Vol. 23, No. 6,
November, 1979).
The loss network's resistance and inductance values are derived from
the computed skin-effect over the frequency range of interest. The
number of sections which make up the equivalent circuit is derived from
criteria based upon the minimum system rise time. For details, see ***
by Tom Giovannini.
*/
Coaxial Cable Model Generation Program
By Tom Giovannini
Revision Level: 08/29/91_1.7
coax: explanation of command line syntax:
coax <subcircuit name> coax_type <type name> \
length <length value (meters) > \
rise_time <minimum system ristime value (seconds)> \
[fit_order <number of frequency points to fit to>] \
[local_physical] \
[ckt_type <spice (default) or touchstone>]
coax: explanation command line arguments:
- The subcircuit name string is required to follow the command
name. It is the name used to name the subcircuit. It must
be eleven charaters or less in length.
- coax_type and it's string value are required and may appear
anywhere in the argument list following the subicircuit name
string. It is used to find the physical information in the
coax.physical file.
- length and it's value in meters are required and may appear
anywhere in the argument list following the subicircuit name
string.
- rise_time and it's value in seconds are required and may appear
anywhere in the argument list following the subicircuit name
string. This is the minimum 0% to 100% system rise time. It is
used to calculate the bandwidth of the model.
- fit_order and it's integer value are optional and may appear
anywhere in the argument list following the subicircuit name
string. It is the maximum number of RL branches which will be
used for the loss network. This value defaults 10.
- local_physical is an optional flag and may appear
anywhere in the argument list following the subicircuit name
string. If present, the program will use the coax.physical file
in the current working directory instead of the library file.
- ckt_type and it's string value are required and may appear
anywhere in the argument list following the subicircuit name
string. If it's value is spice, a spice subcircuit will be listed
to stdout. If it's value is touchstone, a touchstone/mwspice
circuit will be listed to stdout.
coax: explanation coax.physical file parameter line syntax:
- Each line of the coax.physical file provides the value of a
physical parameter for the coax type. The required syntax is:
<coax type string> <parameter name string> <parameter value>
- The program finds the parameters for a particular coax type by
comparing the coax type string with the coax_type string value
given on the coax command line. Parameter lines for more than one
coax type may appear in the coax.physical file.
- The parameter name string is one of the defined coax physical
parameter names (see the following explanation).
- The parameter value is given assuming the required units. (see
the following explanation).
coax: explanation coax.physical file defined parameters:
Key: * Parameter signifies a required parameter.
- Parameter signifies an optional parameter.
* Parameter: a This is the inner conductor radius in meters.
* Parameter: arho This is the inner conductor rho multiplier.
Rho is calculated by multiplying the rho of
copper by this number.
- Parameter: ka This is the inner conductor radius adjust for
the distributed resistance calculation. This is
an optional parameter whose default is 1.0.
* Parameter: b This is the outer conductor inner radius in meters.
- Parameter: bo This is the outer conductor outer radius in meters.
This is and optional parameter whose default is the
value (b + a).
- Parameter: brho This is the outer conductor rho multiplier.
Rho is calculated by multiplying the rho of
copper by this number. This is an optional parameter
whose default is the value given for arho.
- Parameter: kb This is the outer conductor radius adjust for
the distributed resistance calculation. This is
an optional parameter whose default is 1.0.
- Parameter: tand This is the loss tangent of the dielectric. This
an optional parameter whose default is 0.0.
* Parameter: zo This is the nominal impedance of the coax.
* Parameter: er This is the dielectric constant of the dielectric.
=============================================================================
If you think that it is of interest, it is available as is on the ftp site at
step.stanford.edu in the /pub/cpld directory. The shar file for the SUN
is coax.shar, and for the PC it is coax.zip. The readme file is coax.txt.
Let me know if you have any problems.
Tom
[email protected]
408-522-2973