We study critical issues associated with the application of multi-dimensional adaptive. filtering, including space-time adaptive processing (STAP), to real-world radar systems. In particular, transform domain localized techniques are examined from the perspective of receiver beam position and Doppler filter selection relative to mainlobe clutter as well as target returns. It is shown that the selection of asymmetric auxiliary beams offers dramatic improvements in signal-to-interference ratio for targets with low Doppler.