I copied your data file into a "touchstone.txt", and the following sequence produces a usable list-of-(numeric)lists.

(*Import the data from $HomeDirectory/touchstone.txt*)
dataAll = Import["touchstone.txt", "CSV"];

(* From the simple example, we can tell by visual inspection that the \
numbers are in lines 11 and 12. Extract them. *)
dataNum = Take[dataAll, {11, 12}]

The numbers however come up with no commas in between them as follows. We need to post-process.

{{"50.00000 0.07349 179.64844"}, {"62.50000 -0.00239 179.21094"}}

(*Add commas in between the numbers to create a usable list-of-lists \
and convert the numbers back into expressions rather than the strings \
that were read-in. *)
dataList = ToExpression[Flatten[StringSplit[#, " "] & /@ dataNum, 1]]

The result is,

{{50., 0.07349, 179.648}, {62.5, -0.00239, 179.211}}

Check to see if the numbers are real numbers or still strings by taking one and multiplying it.

In[42]:= {dataList[[1, 2]], dataList[[1, 2]]*2}

Out[42]= {0.07349, 0.14698}

The output is a list-of-(numeric)lists as desired.

I wish to attach my second attempt which will read in the textual touchstone file.

1. strips out "!" and "#" as comment lines (expandable to other comment characters)
2. accomodates an arbitrary number of comments,
3. leaves behind the numeric data with any number of rows and columns.
4. No check is done (yet) for any imaginary or missing data like "none" or blanks.

The code can certainly be compressed for brevity. I hope to have made the algorithm readable with the verbose presentation. Thank you.

Attachments:

Thank you Isaac. That is quite clear with the verbose presentation. I might be able to make snippets of it available.

FWIW, the line beginning with a hash is not a comment in a Touchstone file - it must have one, and only one of those lines. I realize that point is nothing to do with the solution though.

Dave

I've been working with files of the touchstone format. When I was surfing for related resources, I found this post. I wrote an import function for the touchstone files of 1.0 version as follows. I hope it can help someone who searches for it.

readsnp[filename_] /; 
  StringContainsQ[filename, ".s" ~~ NumberString ~~ "p"] :=
 Module[{raw, format, complex, nports, sparameters},
  raw = Import[filename, "Table"];
  (*The option line is formatted as: # <frequency unit> <parameter> <
  format> R <n>.*)
  format = Cases[raw, {"#", __}][[1, 4]];
  (*DB for dB-angle(dB=20*lg|magnitude|), MA for magnitude-angle, 
  RI for real-imaginary. Angles are given in degrees.*)
  complex[a_, b_] := 
   Switch[format, "MA", a E^(I \[Pi] b/180), "RI", a + I b, "DB", 
    10^(a/20) E^(I \[Pi] b/180)];
  nports = 
   StringCases[filename, ".s" ~~ n : NumberString ~~ "p" :> n][[1]] //
     FromDigits;
  sparameters = Which[
    nports == 1, 
    Cases[raw, {freq : (_Real | _Integer), 
       s : Repeated[_Real, {2}]} :> {freq, complex@s}],
    (*S-parameters are listed in the order S11, S21, S12, and S22.*)
    nports == 2, 
    Cases[raw, {freq : (_Real | _Integer), 
       s : Repeated[_Real, {8}]} :> {freq, 
       Transpose@Partition[complex @@@ Partition[{s}, 2], 2]}],
    (*The content per line is limited to 4 pairs of parameter data.*)  
    nports > 2,
    SequenceCases[
     raw, {{freq : (_Real | _Integer), sline1 : Repeated[_Real, {8}]},
        srem : Repeated[_List, {Ceiling[nports/4] nports - 
           1}]} :> {freq, 
       Partition[complex @@@ Partition[Flatten@{sline1, srem}, 2], 
        nports]}]
    ]
  ]

Hello Enrico,

I don't know how to find any of the attachments, however I found a sample S2P file here. I used the first file in their list. I attach a notebook which reads this file and extracts the s parameter data. I could not attach the file I used since both s2p and zip are not allowed as attachments.

Kind regards, David

Attachments:

Import S2P.nb