Accurate ground moving target indication (GMTI) and target parameter estimation can be achieved only after sufficient suppression of interfering stationary clutter, particularly for space-based SARs with typically small exo-clutter regions. In its simplest form, this is accomplished using two radar receiver channels, such as the dual receive antenna mode of RADARSAT-2's Moving Object Detection EXperiment (MODEX). In this mode of operation, the full antenna is broken up into two sub-apertures with two parallel receivers to create two independent phase centres. It is well known, however, that a two-aperture approach to GMTI is sub-optimum and that target parameter estimation is often compromised by clutter interference or poor signal-to-clutter ratios. Two degrees-of-freedom are simply not enough to simultaneously suppress the clutter and to accurately estimate the target's properties, such as velocity and location. The investigation, described in this Technical Memorandum, explores several concepts of increasing the spatial diversity for RADARSAT-2, which allows the two-channel SAR system to operate like a three or four channel radar. Owing to the very flexible programming capabilities of the RADARSAT-2 antenna, this can either be accomplished by the toggling of the transmitter between subsequent pulses or via clever transmitter/receiver excitation schemes. A trade-off analysis between number of channels, phase centre separations, and PRF limitations is presented for a system
