This thesis covers microwave experiments carried out on CeCu2Si2 as my master's project. Our data cover a range from 200 MHz to 20 GHz and 80 mK up to 25 K. Our measurements indicate that, in spite of the recent findings from specific-heat measurements, CeCu2Si2 is indeed a d-wave rather than an s-wave superconductor. This is supported by things like uncondensed spectral weight, and the general behavior of e. g. superfluid density.
