Space-Time Adaptive Processing (STAP), using multiple beam and/or aperture arrays, makes possible the rejection of mainbeam and sidelobe jamming, and greatly improves the performance of AI radars in ground clutter. When the antenna ports are used adaptively to suppress interference, monopulse beam-splitting techniques using sum and difference apertures produce significant bias errors and prevent accurate angle measurements. Fortunately, unbiased angle estimates can be obtained using the same processing hardware and software required for STAP. This is being demonstrated with the PC-based Matlab simulation program developed in SBIR I. While this Adaptive Maximum Likelihood Estimate (AMLE) algorithm is believed to be the best and simplest to use with STAP, more programming and testing is needed to bring it into operational use in a timely manner. The amount of calibration data required must be determined. This SBIR II will support further development and testing of this and other angle estimation algorithms using the ASI program with the TI radome simulation code and with field data acquired on the TI range using the ATCK GP3 system. The TI range and GP3 system will be used for demonstrations in near-real time on antennas with and without radomes.