Option Line
Each Touchstone data file must contain an option line (additional option lines after the first one will be ignored). The option line must be the first non-comment line of the file, and is formatted as follows:
# <frequency unit> <parameter> <format> R <n>
where
# marks the beginning of the option line.
frequency unit specifies the unit of frequency. Legal values are
GHz, MHz, KHz, Hz. The default value is GHz.
parameter specifies what kind of network parameter data is
contained in the file. Legal values are:
S for Scattering parameters,
Y for Admittance parameters,
Z for Impedance parameters,
H for Hybrid-h parameters,
G for Hybrid-g parameters.
The default value is S
format specifies the format of the network parameter data
Page 4 10/1/2003
Touchstone File Specification Rev 1.1
pairs. Legal values are:
DB for dB-angle (dB = 20*log10|magnitude|)
MA for magnitude-angle,
RI for real-imaginary.
Angles are given in degrees. Note that this format
does not apply to noise parameters. (Refer to the
“Adding Noise Parameters” section at the end of this
document). The default value is MA.
R n specifies the reference resistance in ohms, where n
is a positive number of ohms (the real impedance to
which the parameters are normalized). The default
reference resistance is 50 ohms.
Option line parameters are separated by one or more whitespace; the option line itself is terminated with a newline character (either CR or CR/LF). If a parameter is missing it assumes the default value. With the exception of the opening # (hash mark) symbol and the value following “R”, option line parameters can appear in any order.
In summary, the option line should read:
For 1-port files: # [HZ/KHZ/MHZ/GHZ] [S/Y/Z/G/H] [MA/DB/RI] [R n]
For 2-port files: # [HZ/KHZ/MHZ/GHZ] [S/Y/Z/G/H] [MA/DB/RI] [R n]
For n-port files: # [HZ/KHZ/MHZ/GHZ] [S/Y/Z/G/H] [MA/DB/RI] [R n]
where the square brackets ([]) indicate optional information; .../.../.../ means
S2P 文件格式规范(推荐！): S2P Guide.pdf
