The detection problem of fluctuating radar targets in the presence of interference (noise and clutter) is considered; the assumed model for both target and clutter is a zero-mean stationary Gaussian random process with assigned power spectral densities. The pertaing optimum linear processor, namely the Optimized Filtering, is derived and its performance are evaluated in different operating conditions, including mismatching with the designed model. Finally, comparison with filtering techniques designed for targets with zero spectral width, i.e. the Moving Target Detector, are performed.