You can use Origin Pro. For that you have to export data from CST plots and then put them to the table in Origin Pro. then by selecting them you can draw multiple graphs in a single plot.
You can use MATLAB and plot multiple graphs in a single plot....
In the MATLAB command window you will find rows and columns like excel sheet. Then, in first column paste X-axis parameter and in next columns paste the values of what you want to plot. After that you use plot, figure((......)), formula....
Dear sir, As above many researcher have mentioned and suggested to use Matlab, CST, HFSS or for that matter Excel and many curve plotting package are available to plot the multiple plot. all these package lacking in print publish quality of single/multiple graph in different graph format. yes all above will definitely plot the data but out put graph will not be as pictorial impressive as what we see in print publish quality . One package which I regularly use and give plot output for single/multiple graph in single window with pictorial impressive and print publish quality in various format of graph in named as SIGMA PLOT. This package I have downloaded from net with no cast. Since this package is exclusively for graph plotting/ data processing it give freedom for data arrangement in single window with pictorial impressive and print publish quality . I would suggest any one who is interested can download the said package and use.
One of the best software for curve plotting in Origin Lab . Use Origin Lab 2018 for multidata plotting . Its really very useful software and also easy to handle. and plots looks very prominent and colorful also.