A few suggestions
1st paragraph - name the university instead of "responsible Universities" (but maybe you were going to do that anyway)
2nd paragraph - maybe say where the University of Wuerzburg is, unless it is obvious to the university you're applying to - "at the University of Wurzburg (Germany)"
3rd paragraph - should be "My academic performance has always been at the top of the [or my] class..." - but I might say something like "As my records show, my academic performance has been exemplary during my time at the University of Wurzburg."
4th paragraph - I struggle a bit with the first sentence. Do you mean something like "I am specifically interested in your Master program because of its strengths in Optic and Radar research, which I am eager to learn more about."
bolded sentence as suggested above