The generation of synthetic environments, in particular clutter, greatly facilitates the characterization of the performance of radars. This is especially the case for radars operating over maritime areas where the sea clutter is highly dependent on the environmental conditions that cannot be controlled or predicted for assessment of performance in trials. Three levels of complexity of the clutter simulation are considered here, according to the different radar modes to be qualified. The first level relates to non-coherent radars while the other levels aim at stimulating coherent Doppler radars. The last level allows generating coherent signals on multiple channels, for instance to validate complex detection modes such as involving Space-Time dependencies (STAP).