Have not checked anything but, I would think you if you are not a permanent resident/citizen you would have to apply for a UK spouse/fiance visa whichever applies and then apply for a schengen visa for your wife to visit you in Germany. Having said that when I was working in Germany for 7 months my wife (then fiance) came to stay with me on a schengen visit visa, I think this gave her 3 months max. stay.