Why MATLAB does not support vector graphic export for smith chart plot

I have a few figures, I exported them all in the same way, but it turned out all are with good resolution but the smith chart ones.

Does anyone encounter the same issue? If yes, did you find any practical way to sort it out?

If ypu have a look to the the image I attached, they are figures in same pdf eported from matlab in same way but the resolution diference is 100% diferent.

Thanks

sm=smithplot();
hold on
sm.ArcTickLabelVisible=0;
sm.CircleTickLabelVisible=0;
sm.Marker = {'+'};
sm.GridBackgroundColor='w';
sm.TitleTopFontSizeMultiplier=1.75;
sm.GridLineWidth=1;
plot(data1,'linewidth',2)
plot(data2,'linewidth',2)

[Jonas]

and HOW did you save the pdf? i have no problems when using this: (see ATTACHMENT!)

without setting content type, matlab sometimes switches to image instead of vector, causing bad quality

smithplot(rand(10)+1i*rand(10));
exportgraphics(gcf,'test.pdf','ContentType','vector');

Warning: Vectorized content might take a long time to create, or it might contain unexpected results. Set 'ContentType' to 'image' for better performance. Click here to not see this message again.

[Araz Garaz]

Thanks Jonas, didn't came to my mind to define the export format within the code, was playing with plotted figure options all the time. Thanks a lot.