How to build bigger S-parameter from smaller S-parameters

I have cable S4P measurements for :

1. Through channel (S4P file)
2. few - NEXT channels of the through channel in section 1 (Near end cross talk) S4P files
3. few FEXT channels if the same through channel in section 1 (FAR end cross talk) S4P files

I need from these to build S16P file, with all this data.

How can I perform this task (that seems to be just placing Matrix data in the correct bigger matrix)

Example of files to use are attached

Thanks,

Roee

Answer 1

[Abhimenyu]

Hi Roee,

I understand that you want to build a S16P file from the provided S4P files. Using MATLAB, you can deconstruct a bigger S-parameter file into smaller ones, e.g., S4P to S2P, but vice versa can only be done by manual array concatenation. Here is the example code for the same:

% Load the S4P file for the through channel 
through_channel_data = read(rfdata.data,'THRU_Molex_TP1-TP4_2mQSFP-DD_RowA_07-2019_P1Tx4-P2Rx4.s4p');  

% Load the S4P files for the NEXT channels 
next_channel1_data = read(rfdata.data,'NEXT_Molex_TP1-TP4_2mQSFP-DD_RowA_07-2019_P1Tx4-P1Rx8.s4p'); 
next_channel2_data = read(rfdata.data,'NEXT_Molex_TP1-TP4_2mQSFP-DD_RowA_07-2019_P1Tx4-P1Rx7.s4p'); 
% ... (load other NEXT channel data files as needed) 

% Load the S4P files for the FEXT channels 
fext_channel1_data = read(rfdata.data,'FEXT_Molex_TP1-TP4_2mQSFP-DD_RowA_07-2019_P1Tx4-P2Rx5.s4p'); 
fext_channel2_data = read(rfdata.data,'FEXT_Molex_TP1-TP4_2mQSFP-DD_RowA_07-2019_P1Tx4-P2Rx3.s4p'); 
% ... (load other FEXT channel data files as needed) 

% Initialize an empty S16P matrix 
s16p_matrix = zeros(4, 4, length(through_channel_data.Freq)); 

% Place the data from the through channel S4P file into the S16P matrix 
s16p_matrix(1:4, 1:4, :, :) = through_channel_data.S_Parameters; 

% Place the data from the NEXT channels S4P files into the S16P matrix
s16p_matrix(1:4, 2:5, :, :) = next_channel1_data.S_Parameters; 
s16p_matrix(1:4, 3:6, :, :) = next_channel2_data.S_Parameters; 
%s16p_matrix(1:4, 4:7, :, :) = next_channel3_data.S_Parameters; 
% ... (place other NEXT channel data into the S16P matrix as needed) 

% Place the data from the FEXT channels S4P files into the S16P matrix 
s16p_matrix(1:4, 9:12, :, :) = fext_channel1_data.S_Parameters; 
s16p_matrix(1:4, 10:13, :, :) = fext_channel2_data.S_Parameters; 
%s16p_matrix(1:4, 11:14, :, :) = fext_channel3_data.S_Parameters; 
%s16p_matrix(1:4, 12:15, :, :) = fext_channel4_data.S_Parameters; 
% ... (place other FEXT channel data into the S16P matrix as needed) 

% Save the S16P matrix as an S16P file 
save('output.s16p', 's16p_matrix'); 

You can substitute rest of your files accordingly and construct the S16P file. For more information follow the below links:

• Process file data for analysis-https://www.mathworks.com/help/releases/R2023a/rf/ug/process-file-data-for-analysis.html
• Rfdata.data-https://www.mathworks.com/help/releases/R2023a/rf/ref/rfckt.rfdata.data.html

Thank you,

Abhimenyu.

Answer 2

[Mark]

It is certainly possible to "concatenate" sparameter data into a larger array and then make a new sparameter. To build an 8x8 out of 4x4s, one could do:

S11 = sparameters('default.s4p');
S12 = sparameters('default.s4p');
S21 = sparameters('default.s4p');
S22 = sparameters('default.s4p');
row1Data = horzcat(S11.Parameters,S12.Parameters);
row2Data = horzcat(S21.Parameters,S22.Parameters);
data = vertcat(row1Data,row2Data); % 8 x 8 x 1496
freqs = S11.Frequencies; % 1496 x 1
SS = sparameters(data,freqs)
% >> SS
% 
% SS = 
% 
%   sparameters with properties:
% 
%       Impedance: 50
%        NumPorts: 8
%      Parameters: [8×8×1496 double]
%     Frequencies: [1496×1 double]

But your use case suggests building a SPICE-like RF Toolbox circuit out of 4x4 nport elements and then "extracting" the sparameters. The nport element is the circuit container for sparameters.

I can't give you an exact answer because I'm not sure how you want to connect your pieces. But it would be something like:

c = circuit;
n = nport('default.s4p');
freqs = n.NetworkData.Frequencies;
add(c,[1 2 3 4 0 0 0 0],n)
n1 = nport('default.s2p');
add(c,[1 0],n1)
n2 = nport('default.s2p');
add(c,[2 0],n2)
n3 = nport('default.s2p');
add(c,[3 0],n3)
n4 = nport('default.s2p');
add(c,[1 0],n4)
setports(c,[1 0],[2 0],[3 0],[4 0])
S = sparameters(c,freqs)

See the example https://www.mathworks.com/help/rf/ug/mos-interconnect-and-crosstalk.html.