You can read through the s2p file using fopen and fscanf functions and store the data in a temporary variable, which you can then write to a csv file, using csvwrite ( https://www.mathworks.com/help/matlab/ref/csvwrite.html ) . Here's how you can go about it:
% Specify the file names
s2pFileName = 'yourFile.s2p';
csvFileName = 'outputFile.csv';
% Open the .s2p file for reading
fid = fopen(s2pFileName, 'rt');
% Skip the header lines. Adjust this based on your file's header lines count, here assuming 5 header lines)
for i = 1:5
fgetl(fid);
end
% Read the data
data = fscanf(fid, '%f', [9 inf])'; % There will typically be 9 columns, 1 for frequency and 8 of phase and magnitudes of different S parameters
% Close the .s2p file
fclose(fid);
% Convert to CSV
csvwrite(csvFileName, data);
Note that this approach assumes there are no comments in the .s2p file. If there are, you will have to incorporate the logic to ignore comment lines while reading through it.
To read the csv file contents, you can use csvread:
data = csvread(csvFileName);
Similar to the previous approach, you can use fopen to open the s2p file for writing. You can write them to the s2p file by iterating through the stored data and using fprintf. Its basically writing the contents to a text file saved with an .s2p extension.
The write loop would look something like this:
s2pFileName = 'outputFile.s2p';
fid = fopen(s2pFileName, 'wt'); %Open s2p file with write permissions