Re: Loading touchstone s2p file

[David Bateman]

address@hidden wrote:
> Hello,
>
> how can i load a touchstone format file *.s2p into my workspace with Octave?
>
> Thanks in advance.
>
> Nacho.
>
>   

Touchstone files have three elements you need to treat..

1) Comments starting with "!" that need to be thrown away
2) Q single option line that define what the contents of the file are 
starting with "#"
3) Data lines that is basically a table of white space separated columns

If you know what is in your file (Frequency in what units, measured 
property Y, S matrix, data in dB/angle, etc and the impedance), then 
just throwing away the comment and option lines and reading the 9 
columns of your matrix should be relatively easy. Assuming your data is  
in real/imaginary parts something like

fid = fopen ("myfile.s2p", "rt");
freq = [];
s11 = [];
s12 = [];
s21 = [];
s22 = [];
while (! feof (fid))
  str = fgets (fid);
  [val , len]= sscanf ("%f %f %f %f %f %f %f %f %f");
  ## Ignore lines with less than 9 elements
  if (len == 9)
    freq = [freq; val(1)];
    s11 = [s11; complex (val(2), val(3))];
    s12 = [s12; complex (val(4), val(5))];
    s21 = [s21; complex (val(6), val(7))];
    s22 = [s22; complex (val(8), val(9))];
  endif
endwhile
fclose(fid)

will do it though inefficiently. These files are typically not very big 
so the above if probably good enough. Its easy to modify the above for 
the case of having your data in dB/angle and magnitude/angle as well.

D.