You may export it with this https://optics.ansys.com/hc/en-us/articles/360034410574-exportfigure-Script-command
But the GUI might not like too many figures open, you will need to close the figure after export.
https://optics.ansys.com/hc/en-us/articles/360034410594-closeall-Script-command
Please note, Ex is a 4 dimension matrix of x,y,z and f. For a plane monitor, it effectively has 3 dimensions. 300 frequency points seem to large. Please make sure you need all the data and your computer is powerful enough.
If you want to view the result, it might be better to save the sweep data into the dataset in the sweep, if the mesh does not change during the sweep. Once the sweep is completed, you can view the result easily. Please refer to https://optics.ansys.com/hc/en-us/articles/360034410514-visualize-Script-command
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