The goal of this work is to establish the accuracy of ray tracing to simulate the radio channel in a Physical Layer Security scenario, where two legitimate users try to take advantage of the intrinsic properties of the channel to generate a shared secret key inaccessible to an eavesdropper. A 3D Ray-Tracing software, including a diffuse scattering model, is employed to simulate spatial correlations in an indoor environment at the frequencies of 2.4 and 5GHz. Measurements, performed with a Vector Network Analyzer, are used to assess the validity of simulated results.