Diffraction loss and deviation of the Doppler spectrum caused by a wind turbine (WT) rotor is analyzed by using a one-dimensional Fresnel diffraction approach applied to the forward scattered signal. To characterize performance degradation of radar and communication systems by a WT, forward scatter path loss and the relative phase shift of the received signal are investigated. Theoretical results are verified by comparison with Uniform Theory of Diffraction (UTD) simulations obtained by FEKO. A joint time-frequency analysis is performed using Short Time Fourier Transform (STFT) to obtain localized time-dependent frequency information about the Doppler deviation.