Subtract a gain value in dB from rfplot

I need to subtract CouplingLoss from the S12 data.

CouplingLoss = -12.0412; % [dB]

H0101=sparameters('H0101-COUPLER A.s2p');

figure(1),clf,rfplot(H0101,1,2,'dB','k')

Answer 1

[Mathieu NOE]

see last section of this help : retrieve the appropriate value to the gain output.

In MATLAB, the rfplot function is used to visualize RF (radio frequency) data, such as S-parameters, reflection coefficients, or RF budget results. To access and plot data using rfplot, you typically need an RF object (e.g., S-parameter object, matching network, or RF budget object). Here's a concise guide:

1. Plotting S-Parameters

To plot S-parameters from an S-parameter object:

% Load or create an S-parameter

object s_obj = sparameters('example.s2p');

% Plot all S-parameters

rfplot(s_obj);

% Plot a specific S-parameter (e.g., S21)

rfplot(s_obj, 2, 1); % Row 2, Column 1

2. Plotting Matching Network Data

To visualize the input reflection coefficient or transducer gain of a matching network:

% Create a matching network object

mn = matchingnetwork('LoadImpedance', 50, 'SourceImpedance', 75);

% Plot reflection coefficient and transducer gain

rfplot(mn);

3. Plotting RF Budget Results

To plot RF budget results for a cascade of RF components:

% Create an RF budget object

rfobj = rfbudget(...);

% Define your RF budget

% Plot RF budget results (e.g., gain vs. frequency)

rfplot(rfobj, 'Gain');

Accessing Data

If you need to access the underlying data for further analysis, you can extract it directly from the RF object (e.g., sparameters, matchingnetwork, or rfbudget) before plotting. For example:

% Access S-parameter

data data = s_obj.Parameters; % 3D matrix of S-parameters

% Access frequencies

freq = s_obj.Frequencies;

% Access RF budget results

gain = rfobj.Gain; % Example: Gain values

This approach allows you to manipulate or analyze the data programmatically before or after plotting.

[Glenn Brigham]

Thank you for the reply.

I'd like to know how to simply subtract a number (loss) from S21 using the rfplot(s_obj,2,1) format.

[Mathieu NOE]

rfplot(s_obj,2,1) alone will do the plot but you won't get direct access to the data to do your substraction . It don't believe there is a way to pass a correction factor inside the rfplot function

so either use the code shown above to access the data of the rfplot object , or maybe as a last alternative, once you have your plot done , you may access the data from the plot axes by using this code and from there it's fairly simply to do the correction

Lines =  findobj(gca, 'Type','line');                        % Return Handles To All 'Line' Objects
x =  Lines.XData(:);                                        % Independent Variable (Force Column Vector With '(:)')
y =  Lines.YData(:);                                        % Dependent Variable  (Force Column Vector With '(:)')
Figure_Table = table(x,y, 'VariableNames',{'X values','Y values'})

if you have saved your plot as a figure , it's simply 2 more lines :

openfig('data points.fig');
set(gcf, 'Visible','off')
Lines =  findobj(gca, 'Type','line');                        % Return Handles To All 'Line' Objects
x =  Lines.XData(:);                                        % Independent Variable (Force Column Vector With '(:)')
y =  Lines.YData(:);                                        % Dependent Variable  (Force Column Vector With '(:)')
Figure_Table = table(x,y, 'VariableNames',{'X values','Y values'})